Tüm alıştırma soruları

2131 soru

Soru 161Soru
Consider the following system of linear equations in variables xx and yy, where kk is a real constant:
kx+4y=8x+ky=k+2\begin{aligned} kx + 4y &= 8 \\ x + ky &= k + 2 \end{aligned}
Which of the following statements are true? Select all that apply.

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Cevap: If k=2k = 2, the system has infinitely many solutions.; If k=2k = -2, the system has no solutions.; If k=0k = 0, the unique solution to the system is (x,y)=(2,2)(x, y) = (2, 2).

Cevap

The correct statements are that setting k=2k = 2 results in infinitely many solutions, setting k=2k = -2 results in no solutions, and setting k=0k = 0 yields the unique solution (2,2)(2, 2).
The system has a coefficient matrix determinant of k24k^2 - 4. Setting k=2k = 2 produces identical equations (x+2y=4x + 2y = 4), giving infinitely many solutions. Setting k=2k = -2 produces parallel equations with different constants (x+2y=4-x + 2y = 4 vs x+2y=0-x + 2y = 0), giving no solutions. Setting k=0k = 0 reduces the system directly to y=2y = 2 and x=2x = 2, confirming the unique point (2,2)(2, 2).

Adım Adım Çözüm

1
Analyze the determinant of the coefficient matrix to identify conditions for unique vs. non-unique solutions.
The coefficient matrix determinant is Δ=kk41=k24=(k2)(k+2)\Delta = k\cdot k - 4\cdot 1 = k^2 - 4 = (k - 2)(k + 2).
If Δ0\Delta \neq 0 (i.e., k±2k \neq \pm 2), the system has a unique solution. If Δ=0\Delta = 0 (i.e., k=2k = 2 or k=2k = -2), the lines are either identical or parallel.
2
Test k=2k = 2 in the system.
Equation 1 becomes 2x+4y=8    x+2y=42x + 4y = 8 \implies x + 2y = 4. Equation 2 becomes x+2y=4x + 2y = 4.
Since the equations are identical, the lines coincide, resulting in infinitely many solutions.
3
Test k=2k = -2 in the system.
Equation 1 becomes 2x+4y=8    x+2y=4-2x + 4y = 8 \implies -x + 2y = 4. Equation 2 becomes x2y=0    x+2y=0x - 2y = 0 \implies -x + 2y = 0.
The slopes are equal (1/21/2) but the y-intercepts differ (22 vs 00), meaning the lines are parallel and distinct, yielding zero solutions.
4
Test k=0k = 0 and k=1k = 1 to evaluate remaining choices.
For k=0k = 0, 4y=8    y=24y = 8 \implies y = 2 and x+0=2    x=2x + 0 = 2 \implies x = 2, giving (2,2)(2, 2). For k=1k = 1, Equation 2 is directly x+y=3x + y = 3.
This verifies that the statement for k=0k = 0 is correct, while the statement for k=1k = 1 claiming x+y=4x + y = 4 is false.

Anahtar Kavram

Parametric Linear Systems and Conditions for Solvability
Soru 162Soru

A survey of 120120 university students evaluated course enrollment in Computer Science and Mathematics. Of the students surveyed, 7070 are enrolled in Computer Science, 6565 are enrolled in Mathematics, and 2525 are enrolled in neither course. How many students are enrolled in both Computer Science and Mathematics?

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Cevap: 40

Cevap

40 students are enrolled in both Computer Science and Mathematics.
The correct answer is 40. From the total population of 120 students, 25 take neither subject, meaning 12025=95120 - 25 = 95 students take at least one subject. According to the Principle of Inclusion-Exclusion, CM=C+MCM|C \cup M| = |C| + |M| - |C \cap M|. Substituting the known values yields 95=70+65CM95 = 70 + 65 - |C \cap M|, which simplifies to 95=135CM95 = 135 - |C \cap M|, giving CM=40|C \cap M| = 40.

Adım Adım Çözüm

1
Calculate the total number of students enrolled in at least one of the two courses.
Total in at least one course = 12025=95120 - 25 = 95.
Subtracting the students enrolled in neither course from the total surveyed gives the union of the two sets, CM|C \cup M|.
2
Apply the Principle of Inclusion-Exclusion for two sets.
CM=C+MCM|C \cup M| = |C| + |M| - |C \cap M|, so 95=70+65CM95 = 70 + 65 - |C \cap M|.
Adding C|C| and M|M| double-counts the students taking both courses, so subtracting the union yields the intersection.
3
Solve for the intersection CM|C \cap M|.
CM=13595=40|C \cap M| = 135 - 95 = 40.
Direct arithmetic evaluation gives the required count of students enrolled in both subjects.

Anahtar Kavram

Principle of Inclusion-Exclusion for Two Sets
Tahmini Süre:1m 0s
Soru 163Soru

In a department of 9090 employees, 5555 speak French, 4545 speak Spanish, and 1010 speak neither French nor Spanish. How many employees speak both French and Spanish?

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Cevap: 20

Cevap

20
Subtracting the 10 employees who speak neither language from the total of 90 leaves 80 employees who speak at least one language. By the principle of inclusion-exclusion, Total(At least one) = French + Spanish - Both. Substituting the known values gives 80 = 55 + 45 - Both, which simplifies to 80 = 100 - Both, so Both = 20.

Adım Adım Çözüm

1
Find the number of employees who speak at least one of the languages
80 employees
Subtract the 10 employees who speak neither language from the total department size of 90.
2
Sum the total counts for each language group
100
Add the number of French speakers (55) to Spanish speakers (45).
3
Calculate the overlap (intersection) using inclusion-exclusion
20 employees
Subtract the count of employees speaking at least one language (80) from the sum of the individual language groups (100).

Anahtar Kavram

Principle of Inclusion-Exclusion for Two Sets
Tahmini Süre:45s
Soru 164Soru

Dataset DD consists of 4040 distinct real numbers arranged in strictly increasing order: x1<x2<<x40x_1 < x_2 < \dots < x_{40}. Let RDR_D, QDQ_D, and σD\sigma_D denote the range, interquartile range, and standard deviation of Dataset DD, respectively.

A new dataset, Dataset EE, is created by replacing each of the 1010 largest numbers (x31,x32,,x40x_{31}, x_{32}, \dots, x_{40}) with the value of x30x_{30}, which represents the 75th75\text{th} percentile of Dataset DD. Let RER_E, QEQ_E, and σE\sigma_E denote the range, interquartile range, and standard deviation of Dataset EE, respectively.

Which of the following statements MUST be true? Select all such statements.

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Cevap: The range of Dataset EE is strictly less than the range of Dataset DD (RE<RDR_E < R_D).; The interquartile range of Dataset EE is equal to the interquartile range of Dataset DD (QE=QDQ_E = Q_D).; The standard deviation of Dataset EE is strictly less than the standard deviation of Dataset DD (σE<σD\sigma_E < \sigma_D).

Cevap

The statements asserting that the range of Dataset E is strictly less than the range of Dataset D (RE<RDR_E < R_D), the interquartile range of Dataset E is equal to the interquartile range of Dataset D (QE=QDQ_E = Q_D), and the standard deviation of Dataset E is strictly less than the standard deviation of Dataset D (σE<σD\sigma_E < \sigma_D) are all correct.
The range of Dataset E decreases because its maximum value is reduced from x40x_{40} to x30x_{30} while its minimum value x1x_1 remains the same. The interquartile range remains unchanged because the boundary values defining the 25th25\text{th} percentile (x10x_{10}) and 75th75\text{th} percentile (x30x_{30}) are not altered. The standard deviation strictly decreases because reducing the 1010 largest values brings them closer to the rest of the distribution, decreasing total variation.

Adım Adım Çözüm

1
Analyze the change in the maximum and minimum values to evaluate the Range.
In Dataset DD, Range RD=x40x1\text{Range } R_D = x_{40} - x_1. In Dataset EE, the maximum element becomes x30x_{30} while the minimum remains x1x_1. Since all numbers are distinct and ordered, x30<x40x_{30} < x_{40}, so RE=x30x1<RDR_E = x_{30} - x_1 < R_D. Thus, RE<RDR_E < R_D is true.
Range is defined as MaximumMinimum\text{Maximum} - \text{Minimum}.
2
Analyze the 25th25\text{th} percentile (Q1Q_1) and 75th75\text{th} percentile (Q3Q_3) to evaluate the Interquartile Range.
For N=40N=40, Q1=x10Q_1 = x_{10} and Q3=x30Q_3 = x_{30}. Dataset EE modifies only the values strictly above x30x_{30} (x31x_{31} through x40x_{40}). Thus x10x_{10} and x30x_{30} retain their exact values in Dataset EE. Therefore, QE=x30x10=QDQ_E = x_{30} - x_{10} = Q_D.
Interquartile range depends solely on Q3Q1Q_3 - Q_1, which relies on position cutoffs that were unaffected.
3
Analyze the effect of pulling extreme upper values inward on the Standard Deviation.
Standard deviation measures overall spread around the mean and can be calculated via pairwise differences Var(X)=12N2i,j(xixj)2\text{Var}(X) = \frac{1}{2N^2} \sum_{i,j} (x_i - x_j)^2. Replacing x31,,x40x_{31}, \dots, x_{40} with x30x_{30} strictly reduces the distances between these upper points and all other points, ensuring σE<σD\sigma_E < \sigma_D.
Reducing the distance of tail observations from the rest of the dataset strictly decreases overall variance and standard deviation.

Anahtar Kavram

Impact of Data Transformations on Measures of Dispersion and Position
Soru 165Soru

The frequency distribution table below summarizes the processing times, in minutes, for a sample of 100 health insurance claims processed by an administrative team.

Claim Processing Time (minutes)Frequency
10t<2010 \le t < 2015
20t<3020 \le t < 3025
30t<4030 \le t < 4035
40t<5040 \le t < 5020
50t<6050 \le t < 605

Which of the following statements regarding this frequency distribution must be true? Select all that apply.

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Cevap: The interval 30t<4030 \le t < 40 contains the median processing time for the dataset.; Exactly 60 percent of the claims required 30 minutes or more to process.; The number of claims in the interval 20t<3020 \le t < 30 represents 25 percent of all claims.

Cevap

The true statements are: the median processing time lies in the interval 30t<4030 \le t < 40; exactly 60 percent of the claims required 30 minutes or more to process; and the number of claims in the interval 20t<3020 \le t < 30 represents 25 percent of all claims.
The statement regarding the median is correct because the 50th and 51st values lie within the cumulative frequency span of 41 to 75, corresponding to 30t<4030 \le t < 40. The statement regarding claims requiring 30 minutes or more is correct because 35+20+5=6035 + 20 + 5 = 60 out of 100 claims is 60 percent. The statement regarding the 20t<3020 \le t < 30 interval is correct because 25 out of 100 claims is exactly 25 percent.

Adım Adım Çözüm

1
Calculate cumulative frequencies to locate the median class interval.
Cumulative frequencies are 15 (10t<2010 \le t < 20), 40 (20t<3020 \le t < 30), 75 (30t<4030 \le t < 40), 95 (40t<5040 \le t < 50), and 100 (50t<6050 \le t < 60). For 100 observations, the 50th and 51st values fall in the 30t<4030 \le t < 40 interval.
The median of an even number N=100N=100 of sorted values is the average of the 50th and 51st values.
2
Calculate the percentage of claims taking 30 minutes or more.
Sum the frequencies for intervals 30\ge 30: 35+20+5=6035 + 20 + 5 = 60. As a percentage of 100 total claims, this is 60100×100%=60%\frac{60}{100} \times 100\% = 60\%.
To find the proportion meeting or exceeding a threshold, sum all class frequencies with lower limits at or above 30 minutes.
3
Evaluate the percentage representation of the 20t<3020 \le t < 30 interval.
Frequency is 25 out of 100 total claims, which equals 25100=25%\frac{25}{100} = 25\%.
The relative frequency of a grouped class is its frequency divided by the total frequency.
4
Determine the lower bound for the estimated mean processing time to evaluate incorrect claims.
Minimum sum = 15(10)+25(20)+35(30)+20(40)+5(50)=275015(10) + 25(20) + 35(30) + 20(40) + 5(50) = 2750. Lower bound mean = 2750/100=27.52750 / 100 = 27.5 minutes.
The absolute minimum mean occurs when every observation equals the lower boundary of its respective interval.
5
Calculate the ratio of claims under 30 minutes to claims 40 minutes or more.
Claims <30< 30 min = 15+25=4015 + 25 = 40. Claims 40\ge 40 min = 20+5=2520 + 5 = 25. Ratio = 40:25=8:540 : 25 = 8 : 5.
Must include all relevant intervals (including 50t<6050 \le t < 60) when computing the denominator for 40\ge 40 minutes.

Anahtar Kavram

Grouped Frequency Distributions, Median Class Identification, and Relative Frequencies
Soru 166Soru

A university archive uses two high-speed scanners, Machine A and Machine B, to digitize manuscript pages. Machine A operates at a constant rate of 6060 pages per hour, and Machine B operates at a constant rate of 8080 pages per hour. On Monday, Machine A starts scanning at 8:00 AM. At 9:30 AM, Machine B is brought online to work alongside Machine A. If both machines continue scanning together at their respective constant rates until a total of 510510 pages have been scanned, at what time will the scanning project be completed?

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Cevap: 12:30 PM

Cevap

12:30 PM
The option stating 12:30 PM is correct. Machine A operates alone from 8:00 AM to 9:30 AM (1.5 hours), completing 60×1.5=9060 \times 1.5 = 90 pages. This leaves 51090=420510 - 90 = 420 pages to be scanned. From 9:30 AM onward, both machines work together at a combined rate of 60+80=14060 + 80 = 140 pages per hour. The remaining 420 pages require 420140=3\frac{420}{140} = 3 hours. Adding 3 hours to 9:30 AM gives a completion time of 12:30 PM.

Adım Adım Çözüm

1
Calculate the number of pages scanned by Machine A during its head start
60 pages/hr×1.5 hours=90 pages60 \text{ pages/hr} \times 1.5 \text{ hours} = 90 \text{ pages}
Machine A operates alone from 8:00 AM to 9:30 AM, which is 1.51.5 hours.
2
Determine the remaining number of pages to be scanned
51090=420 pages510 - 90 = 420 \text{ pages}
Subtract the pages already completed from the total requirement of 510 pages.
3
Calculate the combined scanning rate of both machines
60+80=140 pages/hr60 + 80 = 140 \text{ pages/hr}
When both machines operate simultaneously, their individual rates add together.
4
Calculate the time required to scan the remaining pages
420 pages140 pages/hr=3 hours\frac{420 \text{ pages}}{140 \text{ pages/hr}} = 3 \text{ hours}
Divide the remaining work by the combined rate.
5
Determine the final completion time
9:30 AM+3 hours=12:30 PM9:30 \text{ AM} + 3 \text{ hours} = 12:30 \text{ PM}
Add the combined work duration to the time when both machines began working together (9:30 AM).

Anahtar Kavram

Combined Work Rates with Staggered Start Times
Tahmini Süre:1m 30s
Soru 167Soru

A IT consultant charges a flat setup fee of $150\$150 plus a standard hourly rate of $80\$80 for regular hours worked on a project. For any rush hours worked, the hourly rate increases by 50%50\%. On a recently completed project, the consultant worked a total of tt hours, of which rr hours were rush hours (where 0rt0 \leq r \leq t). Which of the following statements must be true regarding the total charge CC, in dollars, for this project? Select all such statements.

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Cevap: The total charge, in dollars, can be expressed as C=150+80t+40rC = 150 + 80t + 40r.; If the consultant worked a total of 2020 hours and the total charge was $2,150\$2,150, then exactly 1010 of those hours were rush hours.; If no rush hours were worked (r=0r = 0), the average charge per hour, including the setup fee, is 150t+80\frac{150}{t} + 80 dollars per hour.

Cevap

The correct statements are those expressing the total charge as C=150+80t+40rC = 150 + 80t + 40r, determining that 1010 rush hours were worked when total cost is $2,150\$2,150 for 2020 hours, and calculating the average hourly cost as 150t+80\frac{150}{t} + 80 dollars per hour when no rush hours are worked.
The model correctly partitions total hours tt into (tr)(t - r) regular hours at $80\$80/hr and rr rush hours at $120\$120/hr, which simplifies algebraically to C=150+80t+40rC = 150 + 80t + 40r. Solving this equation for t=20t = 20 and C=2150C = 2150 yields r=10r = 10. Furthermore, when r=0r = 0, dividing total charge 150+80t150 + 80t by tt gives 150t+80\frac{150}{t} + 80.

Adım Adım Çözüm

1
Calculate the hourly rush rate from the given percentage increase.
The standard rate is $80\$80/hr. The rush rate is $80×(1+0.50)=$120\$80 \times (1 + 0.50) = \$120/hr.
Rush hours cost 50%50\% more than standard regular hours.
2
Set up the algebraic model for total charge CC using standard hours (tr)(t - r) and rush hours rr.
C=150+80(tr)+120r=150+80t80r+120r=150+80t+40rC = 150 + 80(t - r) + 120r = 150 + 80t - 80r + 120r = 150 + 80t + 40r.
This combines the fixed setup fee with variable costs from regular and rush hours.
3
Evaluate the specific case where total time t=20t = 20 and total cost C=2150C = 2150.
2150=150+80(20)+40r    2150=1750+40r    40r=400    r=102150 = 150 + 80(20) + 40r \implies 2150 = 1750 + 40r \implies 40r = 400 \implies r = 10.
Plugging given values into the algebraic model allows solving for the unknown number of rush hours.
4
Calculate average hourly cost when r=0r = 0.
Average cost =150+80tt=150t+80= \frac{150 + 80t}{t} = \frac{150}{t} + 80.
Average hourly rate is total charge divided by total hours worked.

Anahtar Kavram

Linear algebraic modeling of rate problems with multiple rate components
Soru 168Soru

A university research department needs to form a 4-person delegation consisting of exactly 2 senior researchers and 2 junior researchers. The pool of available candidates contains 5 senior researchers and 6 junior researchers. However, 2 specific senior researchers refuse to serve on the delegation together. How many different 4-person delegations can be formed under these conditions?

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Cevap: 135

Cevap

135 different 4-person delegations can be formed.
To calculate the number of valid delegations, first find the unrestricted number of delegations by multiplying the combinations of senior researchers (52)=10\binom{5}{2} = 10 and junior researchers (62)=15\binom{6}{2} = 15, which equals 150. Next, calculate the number of invalid delegations where both restricted senior researchers are chosen together, which is (22)×(62)=15\binom{2}{2} \times \binom{6}{2} = 15. Subtracting the invalid delegations from the total gives 15015=135150 - 15 = 135.

Adım Adım Çözüm

1
Calculate the total number of possible delegations without any restrictions.
(52)×(62)=10×15=150\binom{5}{2} \times \binom{6}{2} = 10 \times 15 = 150
Choosing 2 senior researchers out of 5 requires combinations, (52)=10\binom{5}{2} = 10. Choosing 2 junior researchers out of 6 requires combinations, (62)=15\binom{6}{2} = 15. By the Fundamental Counting Principle, the total number of unrestricted delegations is 10×15=15010 \times 15 = 150.
2
Calculate the number of invalid delegations that include both restricted senior researchers.
(22)×(62)=1×15=15\binom{2}{2} \times \binom{6}{2} = 1 \times 15 = 15
If both conflicting senior researchers are placed on the delegation, there is only (22)=1\binom{2}{2} = 1 way to select the senior members. The 2 junior researchers can still be selected in (62)=15\binom{6}{2} = 15 ways, giving 15 invalid delegations.
3
Subtract the number of invalid delegations from the total possible delegations.
15015=135150 - 15 = 135
Subtracting the 15 restricted delegations from the 150 total delegations leaves 135 valid delegations.

Anahtar Kavram

Combinations with Exclusion Restrictions and Fundamental Counting Principle
Soru 169Soru

A boutique perfume workshop creates a signature fragrance blend by combining two fragrance oils, Oil A and Oil B. Oil A costs 12perounceandcontains4012 per ounce and contains 40% pure essential oil by volume. Oil B costs 20 per ounce and contains 80% pure essential oil by volume. The perfumer creates a 30-ounce batch of the signature blend at a total cost that averages exactly $15 per ounce. What is the total volume, in ounces, of pure essential oil contained in this 30-ounce blend?

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Cevap: 16.5

Cevap

The total volume of pure essential oil contained in the 30-ounce blend is 16.5 ounces.
To find the total essential oil content, first set up a system of equations for the volumes of Oil A (xx) and Oil B (yy): x+y=30x + y = 30 and 12x+20y=45012x + 20y = 450. Solving this system yields x=18.75x = 18.75 ounces and y=11.25y = 11.25 ounces. Multiplying each by its respective essential oil concentration gives 0.40×18.75=7.50.40 \times 18.75 = 7.5 ounces from Oil A and 0.80×11.25=90.80 \times 11.25 = 9 ounces from Oil B, totaling 16.5 ounces of essential oil.

Adım Adım Çözüm

1
Set up linear equations representing the total volume and total cost of the mixture.
x+y=30x + y = 30 and 12x+20y=45012x + 20y = 450, where xx is ounces of Oil A and yy is ounces of Oil B.
The total cost of the 30-ounce blend at 15perounceis15 per ounce is 15 \times 30 = 450$ dollars.
2
Solve for the quantities of Oil A and Oil B used in the mixture.
x=18.75x = 18.75 ounces of Oil A and y=11.25y = 11.25 ounces of Oil B.
Substituting y=30xy = 30 - x into 12x+20(30x)=45012x + 20(30 - x) = 450 yields 8x=150-8x = -150, giving x=18.75x = 18.75.
3
Compute the amount of pure essential oil contributed by each component and sum them.
0.40(18.75)+0.80(11.25)=7.5+9=16.50.40(18.75) + 0.80(11.25) = 7.5 + 9 = 16.5 ounces.
Oil A contains 40% essential oil by volume and Oil B contains 80% essential oil by volume.

Anahtar Kavram

Systems of Linear Equations and Mixture Modeling
Tahmini Süre:2m 0s
Soru 170Soru

In a reliability study of a power station, Event AA is defined as an inverter system malfunction and Event BB is defined as a battery backup failure during peak hours. The probability that at least one of these two malfunctions occurs is 0.800.80, and the probability that an inverter system malfunction occurs without a battery backup failure is 0.350.35. If Event AA and Event BB are independent events, what is the probability of an inverter system malfunction, P(A)P(A)?

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Cevap: 711\frac{7}{11}

Cevap

The probability of an inverter system malfunction, P(A)P(A), is 711\frac{7}{11}.
The probability of the union of two events can be decomposed as P(AB)=P(ABc)+P(B)P(A \cup B) = P(A \cap B^c) + P(B). Given P(AB)=0.80P(A \cup B) = 0.80 and P(ABc)=0.35P(A \cap B^c) = 0.35, solving yields P(B)=0.45P(B) = 0.45. Because Event AA and Event BB are independent, P(AB)=P(A)P(B)=0.45P(A)P(A \cap B) = P(A)P(B) = 0.45 P(A). Since P(ABc)=P(A)P(AB)P(A \cap B^c) = P(A) - P(A \cap B), we substitute to get 0.35=P(A)0.45P(A)=0.55P(A)0.35 = P(A) - 0.45 P(A) = 0.55 P(A). Solving for P(A)P(A) gives P(A)=0.350.55=711P(A) = \frac{0.35}{0.55} = \frac{7}{11}.

Adım Adım Çözüm

1
Relate the union probability to the difference event ABcA \cap B^c and event BB.
P(AB)=P(ABc)+P(B)P(A \cup B) = P(A \cap B^c) + P(B).
The union of two events AA and BB can be partitioned into the region where only AA occurs (ABcA \cap B^c) and all outcomes in BB.
2
Calculate P(B)P(B) using the given values.
P(B)=P(AB)P(ABc)=0.800.35=0.45=920P(B) = P(A \cup B) - P(A \cap B^c) = 0.80 - 0.35 = 0.45 = \frac{9}{20}.
Subtracting P(ABc)P(A \cap B^c) from P(AB)P(A \cup B) yields P(B)P(B).
3
Apply the definition of independent events to express P(AB)P(A \cap B) in terms of P(A)P(A).
P(AB)=P(A)P(B)=0.45P(A)P(A \cap B) = P(A) \cdot P(B) = 0.45 P(A).
For independent events, the joint probability is the product of their individual probabilities.
4
Set up and solve the equation for P(A)P(A).
P(ABc)=P(A)P(AB)    0.35=P(A)0.45P(A)=0.55P(A)    P(A)=0.350.55=711P(A \cap B^c) = P(A) - P(A \cap B) \implies 0.35 = P(A) - 0.45 P(A) = 0.55 P(A) \implies P(A) = \frac{0.35}{0.55} = \frac{7}{11}.
Dividing 0.350.35 by 0.550.55 yields the exact value of P(A)P(A).

Anahtar Kavram

Probability rules for independent events and set operations on sample spaces
Tahmini Süre:2m 0s
Soru 171Soru

While the ethnomusicologist's fieldwork in the remote highlands was initially dismissed by academics as mere amateur collection, her subsequent analytical monographs proved remarkably __________, uncovering structural patterns in folk melodies that fundamentally transformed scholars' understanding of oral traditions. Which two of the following answer choices, when inserted into the blank, produce completed sentences that are alike in meaning?

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Cevap: trenchant; incisive

Cevap

The words 'trenchant' and 'incisive' both complete the sentence to convey that the monographs were exceptionally insightful and penetrating in their analysis.
Both 'trenchant' and 'incisive' signify sharp, penetrating intellectual insight. Inserting either word emphasizes how the monographs provided keen analysis that overturned previous academic dismissal.

Adım Adım Çözüm

1
Analyze structural signals and context clues in the stem
The contrast signal 'While... initially dismissed' indicates that the subsequent monographs were not superficial or amateurish, but rather highly effective and revealing ('uncovering structural patterns... fundamentally transformed').
Establishing sentence polarity ensures the selected words match the required positive, analytical tone.
2
Identify the target meaning required for the blank
The blank requires an adjective meaning insightful, sharp, penetrating, or highly analytical.
Defining the required contextual meaning allows for targeted option filtering.
3
Evaluate choices for contextual fit and synonymy
'Trenchant' and 'incisive' both mean sharp, clear-cut, and intellectually penetrating. Using either word creates sentences with equivalent meaning.
Sentence Equivalence requires selecting two words that produce identical overall sentence meaning.

Anahtar Kavram

Contextual Synonym Pair Selection in Sentence Equivalence
Soru 172Soru

The behavioral economist observed that the new financial incentives did not merely encourage short-term compliance; furthermore, by altering long-term risk perception, the policy ________ a profound shift in household savings strategies.

Which of the following words, when inserted into the blank, produce sentences that are equivalent in meaning? Select exactly two choices.

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Cevap: induced; engendered

Cevap

The two choices that produce equivalent, logically coherent sentences are 'induced' and 'engendered'.
The sentence relies on the additive continuation transition 'furthermore' and the causal clause 'by altering long-term risk perception'. The initial clause states that the policy encouraged compliance; the second clause expands on this by stating that the policy also brought about a shift in savings strategies. Both 'induced' and 'engendered' mean to cause, produce, or give rise to, making them exact functional synonyms in this context.

Adım Adım Çözüm

1
Analyze the sentence structure and identify transition signals.
The clause opens with 'did not merely encourage...', followed by the continuation signal 'furthermore' and a causal modifier 'by altering long-term risk perception'.
Structural signals dictate whether the blank requires a word that reinforces, elaborates on, or reverses the direction of the preceding clause.
2
Determine the required meaning and tone for the blank.
The blank must mean 'brought about', 'caused', or 'produced' to show how altering risk perception resulted in a profound shift.
The transition 'furthermore' combined with the causal preposition 'by' indicates that the policy created or generated a secondary, broader outcome.
3
Evaluate the choices to find a pair of near-synonyms that both fit the contextual requirement.
'induced' and 'engendered' both mean to bring about or give rise to a condition/action, yielding identical sentence meanings.
Sentence Equivalence requires selecting two distinct options that both fit the syntax and produce logically identical sentences.

Anahtar Kavram

Interpreting Continuation and Causal Transitions in Sentence Equivalence
Soru 173Soru

Passage:
In 1898, Dutch microbiologist Martinus Beijerinck published findings demonstrating that the agent responsible for tobacco mosaic disease was fundamentally distinct from bacteria. Unlike bacterial pathogens, which could be removed from liquid suspension by filtration through porcelain Chamberland filters, the mosaic agent passed unimpeded through the fine pores. Furthermore, Beijerinck observed that while the agent failed to multiply in nutrient broth or cell-free culture media, it proliferated readily when introduced to living, actively growing plant tissues. To describe this novel entity, he coined the term 'contagium vivum fluidum' (contagious living fluid). Although Beijerinck initially hypothesized that the agent was liquid in nature rather than particulate, his crucial insight lay in establishing its absolute dependence on host cellular machinery for replication—a foundational distinction that separated viruses from known cellular microorganisms.

According to the passage, which of the following statements regarding Martinus Beijerinck's research on the tobacco mosaic agent are explicitly supported?

Select all that apply.

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Cevap: The tobacco mosaic agent was capable of passing through porcelain Chamberland filters.; The mosaic agent required living, actively growing host tissue in order to replicate.

Cevap

The statements establishing that the mosaic agent passed through porcelain Chamberland filters and that it required living, actively growing host tissue to replicate are both explicitly supported by the passage.
The passage directly supports two statements: first, that the mosaic agent passed unimpeded through the fine pores of porcelain Chamberland filters; and second, that it proliferated in living plant tissues and depended absolutely on host cellular machinery to replicate.

Adım Adım Çözüm

1
Scan the passage for keywords related to filtration and Chamberland filters.
Located sentence: 'Unlike bacterial pathogens... the mosaic agent passed unimpeded through the fine pores.'
Verifies whether the statement regarding passage through porcelain filters is explicitly supported.
2
Scan the passage for references to nutrient broth and cell-free culture media.
Located sentence: 'Beijerinck observed that while the agent failed to multiply in nutrient broth...'
Evaluates whether the agent could replicate in broth solutions without host tissue.
3
Scan the passage for references to living host tissue requirements.
Located sentences detailing that the agent 'proliferated readily when introduced to living, actively growing plant tissues' and had an 'absolute dependence on host cellular machinery for replication.'
Confirms whether host tissue was required for replication.

Anahtar Kavram

Explicit Detail Retrieval
Soru 174Soru
If xx is a positive integer such that
5442x+1+942x2x+3+2x=2560\frac{\sqrt{54 \cdot 4^{2x+1} + 9 \cdot 4^{2x}}}{\sqrt{2^{x+3} + 2^x}} = 2560
what is the value of xx?
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Cevap: 6

Cevap

The value of xx is 66.
Factoring out common exponential terms inside both radicals yields 22524x=1522x\sqrt{225 \cdot 2^{4x}} = 15 \cdot 2^{2x} for the numerator and 92x=32x/2\sqrt{9 \cdot 2^x} = 3 \cdot 2^{x/2} for the denominator. Dividing these gives 523x/25 \cdot 2^{3x/2}. Equating this to 25602560 results in 23x/2=512=292^{3x/2} = 512 = 2^9, which simplifies to 3x2=9\frac{3x}{2} = 9, or x=6x = 6.

Adım Adım Çözüm

1
Simplify the numerator inside the radical expression.
5442x+1+942x=1522x\sqrt{54 \cdot 4^{2x+1} + 9 \cdot 4^{2x}} = 15 \cdot 2^{2x}
Rewrite 42x+14^{2x+1} as 442x4 \cdot 4^{2x}. Then factor out 42x4^{2x}: 54(442x)+942x=(216+9)42x=22542x54(4 \cdot 4^{2x}) + 9 \cdot 4^{2x} = (216 + 9)4^{2x} = 225 \cdot 4^{2x}. Taking the square root gives 225(22)2x=1522x\sqrt{225} \cdot \sqrt{(2^2)^{2x}} = 15 \cdot 2^{2x}.
2
Simplify the denominator inside the radical expression.
2x+3+2x=32x/2\sqrt{2^{x+3} + 2^x} = 3 \cdot 2^{x/2}
Rewrite 2x+32^{x+3} as 232x=82x2^3 \cdot 2^x = 8 \cdot 2^x. Factoring out 2x2^x gives (8+1)2x=92x(8 + 1)2^x = 9 \cdot 2^x. Taking the square root gives 92x=32x/2\sqrt{9} \cdot \sqrt{2^x} = 3 \cdot 2^{x/2}.
3
Simplify the quotient of the two radical expressions.
1522x32x/2=523x/2\frac{15 \cdot 2^{2x}}{3 \cdot 2^{x/2}} = 5 \cdot 2^{3x/2}
Divide the constants 153=5\frac{15}{3} = 5 and subtract exponents with the same base: 2xx2=3x22x - \frac{x}{2} = \frac{3x}{2}.
4
Equate to 2560 and solve for xx.
x=6x = 6
Divide both sides by 5: 23x/2=25605=5122^{3x/2} = \frac{2560}{5} = 512. Express 512 as a power of 2: 512=29512 = 2^9. Therefore, 3x2=9    3x=18    x=6\frac{3x}{2} = 9 \implies 3x = 18 \implies x = 6.

Anahtar Kavram

Exponent and Radical Simplification using Base Prime Factorization
Tahmini Süre:2m 0s
Soru 175Soru

On the real number line, the set of all real numbers xx that satisfy the inequality 3x711|3x - 7| \le 11 forms a closed interval [a,b][a, b]. What is the value of a+b|a + b|?

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Cevap: 143\frac{14}{3}

Cevap

The value of a+b|a + b| is 143\frac{14}{3}.
Rewriting the inequality 3x711|3x - 7| \le 11 as 113x711-11 \le 3x - 7 \le 11 and solving yields 43x6-\frac{4}{3} \le x \le 6. Thus, the endpoints are a=43a = -\frac{4}{3} and b=6b = 6. Summing these values gives a+b=143a + b = \frac{14}{3}, and taking the absolute value yields 143\frac{14}{3}.

Adım Adım Çözüm

1
Express the absolute value inequality as a compound inequality.
113x711-11 \le 3x - 7 \le 11
An inequality of the form uk|u| \le k for k0k \ge 0 is equivalent to kuk-k \le u \le k.
2
Isolate 3x3x by adding 77 to all parts of the inequality.
11+73x11+7    43x18-11 + 7 \le 3x \le 11 + 7 \implies -4 \le 3x \le 18
Adding a constant to all parts preserves the direction of the inequality.
3
Divide all parts by 33 to solve for xx.
43x6-\frac{4}{3} \le x \le 6
Dividing by a positive number isolates xx without flipping inequality signs.
4
Identify interval bounds aa and bb, then calculate a+b|a + b|.
a=43a = -\frac{4}{3}, b=6    a+b=43+183=143    143=143b = 6 \implies a + b = -\frac{4}{3} + \frac{18}{3} = \frac{14}{3} \implies \left|\frac{14}{3}\right| = \frac{14}{3}
The question asks for the absolute value of the sum of the endpoints of interval [a,b][a, b].

Anahtar Kavram

Absolute value inequalities on the number line and interval endpoints
Soru 176Soru

A quality control inspector evaluates a batch of 1616 precision components. Exactly 1010 of the components meet all engineering specifications, while 66 have minor surface defects. If the inspector randomly selects 22 components from the batch one after another without replacement, what is the probability that both selected components meet all engineering specifications?

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Cevap: 0.375

Cevap

The probability that both selected components meet all engineering specifications is 0.3750.375 (or 38\frac{3}{8}).
Since the components are selected without replacement, the outcome of the second draw depends on the outcome of the first draw. The probability of selecting a qualifying component first is 1016\frac{10}{16}. Given that a qualifying component was drawn first, 99 qualifying components remain out of 1515 total components. The joint probability of both events occurring is 1016×915=90240=38=0.375\frac{10}{16} \times \frac{9}{15} = \frac{90}{240} = \frac{3}{8} = 0.375.

Adım Adım Çözüm

1
Determine the probability of selecting a component meeting specifications on the first draw.
P(E1)=1016=58P(E_1) = \frac{10}{16} = \frac{5}{8}
There are 1010 qualifying components out of 1616 total components.
2
Determine the conditional probability of selecting a second component meeting specifications, given that the first component selected also met specifications.
P(E2E1)=915=35P(E_2 \mid E_1) = \frac{9}{15} = \frac{3}{5}
Because sampling is done without replacement, 99 qualifying components remain out of 1515 total remaining components.
3
Apply the multiplication rule for dependent events to calculate the probability of both events occurring.
P(E1E2)=P(E1)×P(E2E1)=58×35=38=0.375P(E_1 \cap E_2) = P(E_1) \times P(E_2 \mid E_1) = \frac{5}{8} \times \frac{3}{5} = \frac{3}{8} = 0.375
For dependent events, the joint probability is the product of the first event's probability and the conditional probability of the second event.

Anahtar Kavram

Probability of Dependent Events without Replacement
Tahmini Süre:1m 15s
Soru 177Soru
If kk is a positive integer, which of the following expressions is equivalent to 2k+232k1+6k3k112k21\frac{2^{k+2} \cdot 3^{2k-1} + 6^k \cdot 3^{k-1}}{12^k \cdot 2^{-1}} for all values of kk?
Cevabı ve açıklamayı göster

Cevap: 103(32)k\frac{10}{3} \left(\frac{3}{2}\right)^k

Cevap

The expression simplifies to 103(32)k\frac{10}{3} \left(\frac{3}{2}\right)^k.
Factoring the terms in the numerator into base 18k18^k gives 4318k+1318k=5318k\frac{4}{3} \cdot 18^k + \frac{1}{3} \cdot 18^k = \frac{5}{3} \cdot 18^k. The denominator equals 1212k\frac{1}{2} \cdot 12^k. Dividing numerator by denominator yields 5/31/2(1812)k=103(32)k\frac{5/3}{1/2} \cdot \left(\frac{18}{12}\right)^k = \frac{10}{3} \left(\frac{3}{2}\right)^k.

Adım Adım Çözüm

1
Rewrite each term in the numerator using prime base factorization
2k+232k1=2k22(32)k31=42k9k13=4318k2^{k+2} \cdot 3^{2k-1} = 2^k \cdot 2^2 \cdot (3^2)^k \cdot 3^{-1} = 4 \cdot 2^k \cdot 9^k \cdot \frac{1}{3} = \frac{4}{3} \cdot 18^k, and 6k3k1=(23)k3k31=2k9k13=1318k6^k \cdot 3^{k-1} = (2 \cdot 3)^k \cdot 3^k \cdot 3^{-1} = 2^k \cdot 9^k \cdot \frac{1}{3} = \frac{1}{3} \cdot 18^k.
Converting all powers to base 18 allows terms with identical exponential factors to be combined.
2
Combine the terms in the numerator
4318k+1318k=(43+13)18k=5318k\frac{4}{3} \cdot 18^k + \frac{1}{3} \cdot 18^k = \left(\frac{4}{3} + \frac{1}{3}\right) \cdot 18^k = \frac{5}{3} \cdot 18^k.
Adding coefficients of like exponential terms.
3
Simplify the denominator expression
12k21=1212k12^k \cdot 2^{-1} = \frac{1}{2} \cdot 12^k.
Applying the negative exponent rule an=1ana^{-n} = \frac{1}{a^n}.
4
Divide the numerator by the denominator
5318k1212k=5/31/2(1812)k=(532)(32)k=103(32)k\frac{\frac{5}{3} \cdot 18^k}{\frac{1}{2} \cdot 12^k} = \frac{5/3}{1/2} \cdot \left(\frac{18}{12}\right)^k = \left(\frac{5}{3} \cdot 2\right) \cdot \left(\frac{3}{2}\right)^k = \frac{10}{3} \left(\frac{3}{2}\right)^k
Dividing fractions by multiplying by the reciprocal and applying quotient rule for powers with the same exponent.

Anahtar Kavram

Prime base factorization and laws of exponents
Soru 178Soru

An index value I0=1000I_0 = 1{}000 increases over a 6-month period. For each month nn from 1 to 6, the index value InI_n is calculated by increasing the previous month's value In1I_{n-1} by 5%5\% and then rounding the result to the nearest integer (with half-integers rounded up). Let U6=1000×(1.05)6U_6 = 1{}000 \times (1.05)^6 represent the exact unrounded compounded value at month 6.

Which of the following statements must be true? Select all such statements.

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Cevap: I2=1103I_2 = 1{}103; The sequence of monthly increments InIn1I_n - I_{n-1} for n=1,2,,6n = 1, 2, \dots, 6 is strictly increasing.

Cevap

The statement specifying that I2=1103I_2 = 1{}103 and the statement asserting that the sequence of monthly increments InIn1I_n - I_{n-1} is strictly increasing are both correct.
The statement giving I2=1103I_2 = 1{}103 is correct because 1050×1.05=1102.51{}050 \times 1.05 = 1{}102.5, which rounds up to 11031{}103. The statement regarding the sequence of monthly increments is correct because the increments 50,53,55,58,61,6450, 53, 55, 58, 61, 64 strictly increase.

Adım Adım Çözüm

1
Calculate each term of the sequence InI_n by applying a 5% increase and rounding to the nearest integer.
I0=1000I_0 = 1{}000; I1=round(1000×1.05)=1050I_1 = \text{round}(1{}000 \times 1.05) = 1{}050; I2=round(1050×1.05)=round(1102.5)=1103I_2 = \text{round}(1{}050 \times 1.05) = \text{round}(1{}102.5) = 1{}103; I3=round(1103×1.05)=round(1158.15)=1158I_3 = \text{round}(1{}103 \times 1.05) = \text{round}(1{}158.15) = 1{}158; I4=round(1158×1.05)=round(1215.9)=1216I_4 = \text{round}(1{}158 \times 1.05) = \text{round}(1{}215.9) = 1{}216; I5=round(1216×1.05)=round(1276.8)=1277I_5 = \text{round}(1{}216 \times 1.05) = \text{round}(1{}276.8) = 1{}277; I6=round(1277×1.05)=round(1340.85)=1341I_6 = \text{round}(1{}277 \times 1.05) = \text{round}(1{}340.85) = 1{}341.
This establishes the exact sequence of rounded monthly values.
2
Evaluate the statement that I2=1103I_2 = 1{}103.
From Step 1, I2=1103I_2 = 1{}103.
This directly confirms the validity of the first statement.
3
Compute the sequence of monthly increments InIn1I_n - I_{n-1} for n=1,2,,6n = 1, 2, \dots, 6.
Increments: I1I0=50I_1 - I_0 = 50, I2I1=53I_2 - I_1 = 53, I3I2=55I_3 - I_2 = 55, I4I3=58I_4 - I_3 = 58, I5I4=61I_5 - I_4 = 61, I6I5=64I_6 - I_5 = 64.
Since 50<53<55<58<61<6450 < 53 < 55 < 58 < 61 < 64, the sequence of increments is strictly increasing.
4
Compare I6I_6 with U6=1000×(1.05)6U_6 = 1{}000 \times (1.05)^6.
U6=1000×1.3400956...1340.10U_6 = 1{}000 \times 1.3400956... \approx 1{}340.10. Since I6=1341I_6 = 1{}341, I6>U6I_6 > U_6.
The statement claiming U6>I6U_6 > I_6 is false.

Anahtar Kavram

Error propagation in recursive sequence rounding and non-distributivity of exponents over sums
Tahmini Süre:2m 30s
Soru 179Soru

If xx is a negative real number such that (x)3x2=32\sqrt{(-x)^3 \cdot x^2} = 32, what is the value of xx?

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Cevap: 4-4

Cevap

-4
Simplifying the expression inside the radical gives (x)3x2=x5(-x)^3 \cdot x^2 = -x^5. Setting x5=32\sqrt{-x^5} = 32 and squaring both sides gives x5=322=1024-x^5 = 32^2 = 1024, which means x5=1024x^5 = -1024. The fifth root of 1024-1024 is 4-4. Since 4-4 is a negative real number, it satisfies all conditions of the problem.

Adım Adım Çözüm

1
Simplify the expression under the square root
Since (x)3=x3(-x)^3 = -x^3, we have (x)3x2=(x3)x2=x5(-x)^3 \cdot x^2 = (-x^3) \cdot x^2 = -x^5.
Applying exponent addition rules xaxb=xa+bx^a \cdot x^b = x^{a+b} and odd power rules for negative quantities.
2
Square both sides of the equation to eliminate the square root
x5=322=1024-x^5 = 32^2 = 1024.
Squaring both sides of x5=32\sqrt{-x^5} = 32 isolates the radicand.
3
Solve for x
x5=1024    x=10245=4x^5 = -1024 \implies x = \sqrt[5]{-1024} = -4.
Taking the 5th root of 1024=(2)10=(4)5-1024 = (-2)^{10} = (-4)^5 yields x=4x = -4, which satisfies the given condition x<0x < 0.

Anahtar Kavram

Simplifying expressions with powers and square roots involving negative variables.
Tahmini Süre:1m 15s
Soru 180Soru

For all real numbers xx and yy such that xyx \neq y, xyx \neq -y, and x2+y20x^2 + y^2 \neq 0, consider the algebraic expression:

E(x,y)=x4y4x3x2y+xy2y3E(x, y) = \frac{x^4 - y^4}{x^3 - x^2y + xy^2 - y^3}

Which of the following expressions are equivalent to E(x,y)E(x, y) for all valid values of xx and yy? Select all such expressions.

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Cevap: x2y2xy\frac{x^2 - y^2}{x - y}; x3+y3x2xy+y2\frac{x^3 + y^3}{x^2 - xy + y^2}

Cevap

The expressions equivalent to E(x,y)E(x, y) are x2y2xy\frac{x^2 - y^2}{x - y} and x3+y3x2xy+y2\frac{x^3 + y^3}{x^2 - xy + y^2}.
Simplifying E(x,y)E(x, y) by factoring both numerator and denominator yields x+yx + y. The option with x2y2xy\frac{x^2 - y^2}{x - y} simplifies directly to x+yx + y by canceling (xy)(x - y). The option with x3+y3x2xy+y2\frac{x^3 + y^3}{x^2 - xy + y^2} uses the sum of cubes identity to factor the numerator into (x+y)(x2xy+y2)(x + y)(x^2 - xy + y^2), which also cancels down to x+yx + y. Both of these options are mathematically identical to E(x,y)E(x, y).

Adım Adım Çözüm

1
Factor the numerator of E(x,y)E(x, y) using the difference of squares identity twice.
x4y4=(x2y2)(x2+y2)=(xy)(x+y)(x2+y2)x^4 - y^4 = (x^2 - y^2)(x^2 + y^2) = (x - y)(x + y)(x^2 + y^2)
Decomposing higher-power binomials into linear and quadratic factors enables algebraic simplification.
2
Factor the denominator of E(x,y)E(x, y) by grouping terms.
x3x2y+xy2y3=x2(xy)+y2(xy)=(xy)(x2+y2)x^3 - x^2y + xy^2 - y^3 = x^2(x - y) + y^2(x - y) = (x - y)(x^2 + y^2)
Grouping adjacent terms with shared factors allows factoring out (xy)(x - y).
3
Simplify the full expression E(x,y)E(x, y) by canceling common non-zero factors.
E(x,y)=(xy)(x+y)(x2+y2)(xy)(x2+y2)=x+yE(x, y) = \frac{(x - y)(x + y)(x^2 + y^2)}{(x - y)(x^2 + y^2)} = x + y
Since xyx \neq y and x2+y20x^2 + y^2 \neq 0, the factors (xy)(x - y) and (x2+y2)(x^2 + y^2) cancel completely.
4
Evaluate the given options to determine which simplify to x+yx + y.
x2y2xy=x+y\frac{x^2 - y^2}{x - y} = x + y and x3+y3x2xy+y2=x+y\frac{x^3 + y^3}{x^2 - xy + y^2} = x + y, whereas x3y3x2+xy+y2=xy\frac{x^3 - y^3}{x^2 + xy + y^2} = x - y and x2y2x+y=xy\frac{x^2 - y^2}{x + y} = x - y.
Matching each option's fully simplified form to x+yx + y identifies all valid equivalent expressions.

Anahtar Kavram

Simplifying rational expressions by polynomial factoring (grouping, difference of squares, and sum of cubes).
ÖncekiSayfa 9 / 107Sonraki
Tüm alıştırma soruları — GRE General Test | Examkin