Linear Inequalities in One Variable Alıştırma Soruları — SAT

Soru 1Soru →

Let $p$ and $q$ be constants. The inequality $p(x - 5) < q(x + 4)$ has the solution set $x > 2$ . If $p - q = -3$ , what is the value of $p + q$ ?

1

39

-1

-3

Cevabı ve açıklamayı göster

Cevap: -1

Cevap

-1

The correct answer is

-1

. Expanding the inequality

p(x - 5) < q(x + 4)

gives

px - 5p < qx + 4q

. Grouping the

x

terms yields

(p - q)x < 5p + 4q

. Since

p - q = -3

, which is negative, dividing both sides by

p - q

reverses the inequality to

x > \frac{5p + 4q}{p - q}

. Comparing this to the given solution

x > 2

, the boundary value must satisfy

\frac{5p + 4q}{-3} = 2

, which simplifies to

5p + 4q = -6

. Using the system of equations

p - q = -3

and

5p + 4q = -6

, we find

p = -2

and

q = 1

. Therefore, the value of

p + q

is

-2 + 1 = -1

.

Adım Adım Çözüm

1

Expand both sides of the inequality and group the terms with

x

on one side.

(p - q)x < 5p + 4q

Expanding

p(x - 5) < q(x + 4)

gives

px - 5p < qx + 4q

. Subtracting

qx

and adding

5p

to both sides yields

px - qx < 5p + 4q

, which factors to

(p - q)x < 5p + 4q

.

2

Determine the direction of the inequality when isolating

x

.

x > \frac{5p + 4q}{p - q}

Since we are given

p - q = -3

, the quantity

p - q

is negative. Dividing both sides of the inequality by a negative value reverses the inequality symbol from

<

to

>

.

3

Equate the resulting boundary expression to the boundary of the given solution set

x > 2

.

5p + 4q = -6

The boundary value of the solution set is

2

, so we set

\frac{5p + 4q}{p - q} = 2

. Substituting

p - q = -3

gives

\frac{5p + 4q}{-3} = 2

, which simplifies to

5p + 4q = -6

.

4

Solve the system of linear equations for

p

and

q

.

p = -2

and

q = 1

We have the system of equations

p - q = -3

and

5p + 4q = -6

. From the first equation,

p = q - 3

. Substituting this into the second equation gives

5(q - 3) + 4q = -6 \implies 9q - 15 = -6 \implies 9q = 9 \implies q = 1

. Substituting

q = 1

back into

p = q - 3

gives

p = -2

.

5

Calculate the value of

p + q

.

-1

Adding the values of

p

and

q

gives

p + q = -2 + 1 = -1

.

Anahtar Kavram

Solving linear inequalities in one variable with variable coefficients and applying sign reversal rules.

Soru 2Soru →

If $-2(x - 5) \geq 4$ , what is the maximum possible value of $x$ ?

Cevabı ve açıklamayı göster

Cevap: 3

Cevap

3

Distributing the

-2

on the left side of the inequality

-2(x - 5) \geq 4

yields

-2x + 10 \geq 4

. Subtracting

10

from both sides gives

-2x \geq -6

. Dividing both sides by

-2

and reversing the inequality sign results in

x \leq 3

. The maximum possible value is therefore 3.

Adım Adım Çözüm

1

Distribute

-2

to the terms inside the parentheses.

-2x + 10 \geq 4

Applying the distributive property simplifies the inequality.

2

Subtract

10

from both sides of the inequality.

-2x \geq -6

This isolates the variable term on the left side.

3

Divide both sides of the inequality by

-2

and reverse the inequality sign.

x \leq 3

Dividing both sides of an inequality by a negative number reverses the direction of the inequality.

Anahtar Kavram

Solving linear inequalities in one variable using the distributive property and division by negative numbers.

Soru 3Soru →

Which of the following represents all possible values of $x$ that satisfy the inequality $-4(x + 3) \leq 8$ ?

x \geq -5

x \leq -5

x \geq 1

x \geq -4

Cevabı ve açıklamayı göster

Cevap: $x \geq -5$

Cevap

x \geq -5

To solve

-4(x + 3) \leq 8

, first distribute the

-4

to obtain

-4x - 12 \leq 8

. Next, add

12

to both sides to isolate the variable term, resulting in

-4x \leq 20

. Finally, divide both sides by

-4

and reverse the inequality sign because of division by a negative number, which yields

x \geq -5

.

Adım Adım Çözüm

1

Distribute the coefficient outside the parentheses to the terms inside.

-4x - 12 \leq 8

Multiplying

-4

by

x

and

-4

by

3

simplifies the left side of the inequality.

2

Isolate the variable term by adding

12

to both sides of the inequality.

-4x \leq 20

Adding

12

eliminates the constant term on the left side:

8 + 12 = 20

.

3

Divide both sides of the inequality by

-4

and reverse the inequality sign.

x \geq -5

Dividing by a negative number reverses the direction of the inequality symbol:

20 / -4 = -5

.

Anahtar Kavram

Solving linear inequalities in one variable using the distributive property and division by a negative number.

Tahmini Süre:45s

Soru 4Soru →

A gym membership costs $\$35$ per month plus an additional $\$5$ per fitness class attended. If a member wants to spend at most $\$65$ in a single month, what is the maximum number of fitness classes the member can attend?

Cevabı ve açıklamayı göster

Cevap: 6

Cevap

The maximum number of fitness classes the member can attend is

6

.

Let

c

represent the number of classes. The inequality representing the budget constraint is

35 + 5c \le 65

. Subtracting

35

from both sides of the inequality yields

5c \le 30

. Dividing both sides by

5

yields

c \le 6

. Since the number of classes must be a whole number, the maximum number of classes the member can attend is

6

.

Adım Adım Çözüm

1

Set up the inequality representing the situation.

35 + 5c \le 65

The cost of the membership is a fixed

\$35

plus

\$5

per class

c

, and this total must not exceed

\$65

.

2

Subtract

35

from both sides of the inequality to isolate the variable term.

5c \le 30

Isolating the term with the variable allows us to solve for

c

.

3

Divide both sides by

5

to find the solution range for the number of classes.

c \le 6

Dividing by the coefficient of the variable gives the upper limit for the number of classes.

Anahtar Kavram

Solving one-variable linear inequalities in a real-world context.

Soru 5Soru →

Which of the following inequalities is equivalent to $-3(x - 4) < 15$ ?

x > -1

x < -1

x > -9

x < -9

Cevabı ve açıklamayı göster

Cevap: $x > -1$

Cevap

The inequality

x > -1

The correct answer is obtained by dividing both sides of the inequality

-3(x - 4) < 15

by

-3

, which reverses the inequality symbol to yield

x - 4 > -5

. Adding

4

to both sides isolates the variable, resulting in

x > -1

. Alternatively, distributing the

-3

first yields

-3x + 12 < 15

, which simplifies to

-3x < 3

, and dividing by

-3

with a sign flip yields

x > -1

.

Adım Adım Çözüm

1

Divide both sides of the inequality

-3(x - 4) < 15

by

-3

.

x - 4 > -5

Dividing an inequality by a negative number reverses the direction of the inequality symbol.

2

Add

4

to both sides of the inequality to isolate

x

.

x > -1

Adding a constant to both sides preserves the inequality and isolates the variable

x

.

Anahtar Kavram

Solving linear inequalities in one variable involving distribution and negative coefficients.

Soru 6Soru →

In a certain video game, a player earns 15 points for completing a level and loses 3 points for each hint they use. If a player wants to score at least 6 points on a level, what is the maximum number of hints they can use?

Cevabı ve açıklamayı göster

Cevap: 3

Cevap

The maximum number of hints the player can use is 3.

To find the maximum number of hints, we construct the inequality representing the player's score:

15 - 3h \geq 6

, where

h

is the number of hints used. Subtracting 15 from both sides gives

-3h \geq -9

. Dividing both sides by

-3

and reversing the inequality sign yields

h \leq 3

. This means the player can use at most 3 hints to achieve a score of at least 6 points. Thus, the maximum number of hints is 3.

Adım Adım Çözüm

1

Set up the inequality representing the score requirement.

15 - 3h \geq 6

The starting score is 15, and 3 points are lost for each hint

h

. The final score must be at least (greater than or equal to) 6.

2

Subtract 15 from both sides of the inequality.

-3h \geq -9

This isolates the variable term on the left side of the inequality.

3

Divide both sides by -3 and flip the inequality sign.

h \leq 3

Dividing both sides of an inequality by a negative number reverses the direction of the inequality sign.

Anahtar Kavram

Solving multi-step linear inequalities with negative coefficients

Tahmini Süre:45s

Soru 7Soru →

For which values of $x$ is the inequality $2 - 3(x + 4) \geq 11$ true?

x \leq -7

x \geq -7

x \leq 1

x \leq -1

Cevabı ve açıklamayı göster

Cevap: $x \leq -7$

Cevap

The correct inequality is

x \leq -7

.

Subtracting 2 from both sides of

2 - 3(x + 4) \geq 11

gives

-3(x + 4) \geq 9

. Dividing both sides by the negative number

-3

requires reversing the inequality sign, yielding

x + 4 \leq -3

. Subtracting 4 from both sides completes the isolation of

x

, yielding the correct solution

x \leq -7

.

Adım Adım Çözüm

1

Subtract 2 from both sides of the inequality.

-3(x + 4) \geq 9

This isolates the term containing the parentheses on one side of the inequality.

2

Divide both sides of the inequality by

-3

and reverse the direction of the inequality sign.

x + 4 \leq -3

Dividing an inequality by a negative number requires reversing the direction of the inequality symbol to maintain equivalence.

3

Subtract 4 from both sides of the inequality.

x \leq -7

This isolates the variable

x

on one side of the inequality, providing the final solution set.

Anahtar Kavram

Solving multi-step linear inequalities in one variable, including distributing negative constants and reversing the inequality direction when dividing by a negative number.

Soru 8Soru →

A local delivery service charges a flat fee of $12$ dollars plus $1.50$ dollars per mile to deliver a package. If a customer wants to spend no more than $30$ dollars for a package delivery, what is the maximum number of miles the delivery service can travel?

Cevabı ve açıklamayı göster

Cevap: 12

Cevap

The maximum number of miles the delivery service can travel is 12.

The total delivery cost is the sum of the flat fee (

12

dollars) and the rate per mile (

1.50

dollars multiplied by

m

miles), which is represented by

1.50m + 12

. Since the total cost cannot exceed

30

dollars, the inequality is

1.50m + 12 \leq 30

. Subtracting

12

from both sides gives

1.50m \leq 18

. Dividing both sides by

1.50

yields

m \leq 12

. Thus, the maximum distance the delivery service can travel is

12

miles.

Adım Adım Çözüm

1

Set up the inequality representing the delivery cost constraint.

1.50m + 12 \leq 30

The total cost of the delivery is the flat fee of

12

dollars plus

1.50

dollars per mile,

m

, which must be less than or equal to the budget of

30

dollars.

2

Subtract 12 from both sides of the inequality.

1.50m \leq 18

To isolate the variable term, subtract the constant flat fee from both sides of the inequality.

3

Divide both sides of the inequality by 1.50.

m \leq 12

Dividing by the per-mile rate calculates the maximum distance constraint on the variable

m

.

Anahtar Kavram

Setting up and solving a one-variable linear inequality to determine a maximum boundary value in context.

Soru 9Soru →

Which of the following represents all possible values of $x$ that satisfy the inequality $-2(x - 5) > 6$ ?

x < -8

x < 2

x > 2

x < 8

Cevabı ve açıklamayı göster

Cevap: $x < 2$

Cevap

The inequality is satisfied when

x < 2

.

Dividing both sides of the inequality

-2(x - 5) > 6

by

-2

yields

x - 5 < -3

, where the inequality sign is reversed because of division by a negative number. Adding

5

to both sides of

x - 5 < -3

results in

x < 2

.

Adım Adım Çözüm

1

Divide both sides of the inequality

-2(x - 5) > 6

by

-2

.

x - 5 < -3

Dividing both sides of an inequality by a negative number requires reversing the direction of the inequality sign.

2

Add

5

to both sides of the inequality to isolate

x

.

x < 2

To solve for

x

, eliminate the constant term

-5

on the left side of the inequality.

Anahtar Kavram

Solving linear inequalities in one variable, including reversing the inequality sign when multiplying or dividing by a negative number.

Soru 10Soru →

Let $c$ be a constant such that $c < 0$ . If $c(x - 3) \leq 4(x + c)$ , which of the following inequalities must be true?

x \leq \frac{7c}{c - 4}

x \geq \frac{c}{c - 4}

x \geq \frac{7c}{c - 4}

x \geq \frac{7c}{c + 4}

Cevabı ve açıklamayı göster

Cevap: $x \geq \frac{7c}{c - 4}$

Cevap

x \geq \frac{7c}{c - 4}

The correct answer is obtained by first distributing terms on both sides to get

cx - 3c \leq 4x + 4c

. Rearranging the terms to isolate the variable

x

on one side yields

(c - 4)x \leq 7c

. Since

c

is a negative constant (

c < 0

), the coefficient

(c - 4)

must also be negative. Dividing both sides of the inequality by this negative coefficient requires reversing the direction of the inequality sign, which yields the final result.

Adım Adım Çözüm

1

Distribute the constants on both sides of the inequality.

cx - 3c \leq 4x + 4c

This simplifies the parentheses so that variable terms can be grouped.

2

Group all terms with

x

on the left side and terms with

c

on the right side.

cx - 4x \leq 7c

Isolating the variable terms on one side makes it possible to factor and solve for

x

.

3

Factor out

x

on the left side of the inequality.

(c - 4)x \leq 7c

This expresses the left side as a product of

x

and a single coefficient.

4

Analyze the sign of the coefficient

(c - 4)

given that

c < 0

.

c - 4 < 0

Since

c

is less than

0

, subtracting

4

from

c

must result in a value less than

-4

, which is strictly negative.

5

Divide both sides of the inequality by

(c - 4)

and flip the inequality symbol.

x \geq \frac{7c}{c - 4}

Dividing an inequality by a negative number requires reversing the direction of the inequality sign.

Anahtar Kavram

Solving linear inequalities by isolating the variable, and correctly reversing the inequality direction when multiplying or dividing by a negative variable parameter.

Soru 11Soru →

If the solution to the inequality $a(2 - 3x) - 4(x + 3) \ge 12$ , where $a$ is a constant, is $x \le -1$ , what is the value of $a$ ?

Cevabı ve açıklamayı göster

Cevap: 4

Cevap

The value of

a

is

4

.

To solve the inequality

a(2 - 3x) - 4(x + 3) \ge 12

, we first expand it to get

2a - 3ax - 4x - 12 \ge 12

. Grouping the

x

terms gives

(-3a - 4)x \ge 24 - 2a

. Since the inequality's solution is

x \le -1

, the direction of the inequality must flip, which means the coefficient of

x

, namely

-3a - 4

, must be negative. Dividing both sides by this coefficient gives the boundary value of the inequality as

\frac{24 - 2a}{-3a - 4}

. Setting this boundary equal to

-1

yields

24 - 2a = 3a + 4

, which simplifies to

5a = 20

, or

a = 4

. Since

a = 4

makes the coefficient

-3(4) - 4 = -16

negative, the solution holds.

Adım Adım Çözüm

1

Expand the inequality using the distributive property.

2a - 3ax - 4x - 12 \ge 12

This allows us to separate and group the terms containing the variable

x

and the constant terms.

2

Group like terms and isolate the variable terms on the left-hand side.

(-3a - 4)x \ge 24 - 2a

By combining the coefficients of

x

and adding

12 - 2a

to both sides, we prepare the inequality to solve for

x

.

3

Determine the effect of dividing by the variable's coefficient.

Since the given solution is

x \le -1

, the inequality sign flipped from

\ge

to

\le

. Therefore, the coefficient

-3a - 4

must be negative.

Multiplying or dividing both sides of an inequality by a negative number reverses the direction of the inequality sign.

4

Set the boundary value of the solution equal to

-1

and solve for

a

.

a = 4

Setting the boundary of the inequality

\frac{24 - 2a}{-3a - 4}

equal to

-1

allows us to find the specific constant

a

that produces this solution set.

Anahtar Kavram

Solving linear inequalities in one variable involving parameters and sign flips.

Soru 12Soru →

For a constant $k$ , the inequality $\frac{k - 3x}{2} > \frac{5x + 3}{4}$ has exactly 4 positive integer solutions for $x$ . If $k$ is an integer, how many possible values of $k$ are there?

Cevabı ve açıklamayı göster

Cevap: 6

Cevap

The number of possible integer values for

k

is 6.

Simplifying the inequality gives

x < \frac{2k - 3}{11}

. For this inequality to have exactly 4 positive integer solutions, the solution set must contain only the integers 1, 2, 3, and 4. This requires the boundary

\frac{2k - 3}{11}

to satisfy

4 < \frac{2k - 3}{11} \le 5

. Solving for

k

gives

23.5 < k \le 29

. The integers in this interval are 24, 25, 26, 27, 28, and 29, which total 6 values.

Adım Adım Çözüm

1

Multiply both sides of the inequality by 4.

2(k - 3x) > 5x + 3

Clearing the denominators makes the inequality easier to solve.

2

Distribute the 2 on the left side.

2k - 6x > 5x + 3

Expanding terms allows us to group variables.

3

Add

6x

to both sides and subtract 3 from both sides.

11x < 2k - 3

Grouping

x

on one side and parameter terms on the other side.

4

Divide by 11.

x < \frac{2k - 3}{11}

Isolating

x

gives the boundary for the solution set.

5

Establish the range for the boundary term

\frac{2k - 3}{11}

.

4 < \frac{2k - 3}{11} \le 5

For the inequality to contain exactly the positive integers 1, 2, 3, and 4, the boundary must lie strictly above 4 and less than or equal to 5.

6

Solve the compound inequality for

k

.

23.5 < k \le 29

Performing algebraic operations on all parts of the inequality to isolate

k

.

7

Identify and count all integer solutions for

k

.

6 integers (24, 25, 26, 27, 28, 29)

Counting the integers in the range

(23.5, 29]

yields the final answer.

Anahtar Kavram

Solving linear inequalities in one variable with parameter constraints and identifying integer solution sets.

Tahmini Süre:3m 0s

Soru 13Soru →

In the inequality $-2(3x - k) - 5(x + 1) > 17$ , $k$ is an integer constant. If the maximum integer value of $x$ that satisfies the inequality is $2$ , what is the least possible value of $k$ ?

Cevabı ve açıklamayı göster

Cevap: 23

Cevap

The correct answer is 23.

By simplifying the inequality to

x < \frac{2k - 22}{11}

, we establish that the upper bound of the solution interval must be strictly greater than

2

but less than or equal to

3

for

2

to be the maximum integer solution. Solving the resulting compound inequality

2 < \frac{2k - 22}{11} \le 3

yields

22 < k \le 27.5

. The smallest integer within this range is

23

.

Adım Adım Çözüm

1

Distribute the constants on the left side of the inequality.

-6x + 2k - 5x - 5 > 17

Applying the distributive property simplifies the expression and removes the parentheses.

2

Combine like terms on the left side and isolate the

x

term.

-11x + 2k - 5 > 17 \implies -11x > 22 - 2k

Grouping

x

terms together and moving the constant terms to the other side prepares the inequality for division.

3

Divide both sides by

-11

and flip the inequality sign.

x < \frac{22 - 2k}{-11} \implies x < \frac{2k - 22}{11}

Dividing by a negative number reverses the direction of the inequality sign from greater-than (

>

) to less-than (

<

).

4

Set up the inequality for the maximum integer solution to be

2

.

2 < \frac{2k - 22}{11} \le 3

For

2

to be the largest integer satisfying

x < L

(where

L

is the boundary),

2

must be strictly less than

L

, and

L

must be less than or equal to the next integer,

3

.

5

Solve the compound inequality for the parameter

k

.

22 < 2k - 22 \le 33 \implies 44 < 2k \le 55 \implies 22 < k \le 27.5

Multiplying all parts by 11, adding 22, and dividing by 2 isolates

k

.

6

Find the least integer value of

k

in the interval

(22, 27.5]

.

23

The integers that satisfy

22 < k \le 27.5

are

23, 24, 25, 26,

and

27

. The least of these values is

23

.

Anahtar Kavram

Solving linear inequalities in one variable involving parameter bounds, negative coefficients, and integer solution constraints.

Soru 14Soru →

An online service provider offers two monthly subscription plans. Under Plan A, the customer pays a flat monthly fee of $C$ dollars. Under Plan B, the monthly cost, in dollars, is determined by the expression $1.5(20 - x) - 0.8(3x - 5)$ , where $x$ is the number of premium features the customer uses. The provider wants Plan B to be strictly cheaper than Plan A for any customer who uses more than 4 premium features. If $C$ is an integer, what is the minimum possible value of $C$ ?

Cevabı ve açıklamayı göster

Cevap: 19

Cevap

19

To find the minimum integer value of

C

, we simplify Plan B's cost expression to

34 - 3.9x

and set up the inequality

34 - 3.9x < C

. Solving for

x

by dividing by

-3.9

and reversing the inequality sign gives

x > \frac{34 - C}{3.9}

. For Plan B to be cheaper than Plan A for all customers using more than 4 features, the solution set

x > \frac{34 - C}{3.9}

must contain the interval

x > 4

. This requires the boundary point to be at most 4, so

\frac{34 - C}{3.9} \le 4

. Solving this inequality yields

C \ge 18.4

. The smallest integer value greater than or equal to

18.4

is 19.

Adım Adım Çözüm

1

Simplify the cost expression for Plan B

34 - 3.9x

To combine like terms and express Plan B's cost in standard linear form.

2

Set up the inequality stating Plan B is strictly cheaper than Plan A

34 - 3.9x < C

Plan B is cheaper than Plan A when its cost is less than

C

dollars.

3

Solve the inequality for

x

in terms of

C

x > \frac{34 - C}{3.9}

Isolating

x

allows us to find the threshold number of premium features, remembering to reverse the inequality direction when dividing by the negative coefficient

-3.9

.

4

Relate the threshold condition to the given minimum number of premium features

\frac{34 - C}{3.9} \le 4

For Plan B to be cheaper for any

x > 4

, the solution interval

x > \frac{34 - C}{3.9}

must cover the entire interval

x > 4

. Thus, the boundary point must be at most 4.

5

Solve the boundary inequality for

C

C \ge 18.4

Multiplying by

3.9

and isolating

C

gives the lower bound for the cost of Plan A.

6

Find the minimum integer value for

C

19

Since

C

must be an integer and at least

18.4

, the smallest integer that satisfies this inequality is 19.

Anahtar Kavram

Solving linear inequalities in one variable with parameter constraints and real-world conditions.

Soru 15Soru →

For a constant $a$ , the inequality $5x - a(3 - 2x) \ge 4$ has a solution set of the form $x \le d$ , where $d$ is a constant. Which of the following must be true about the value of $a$ ?

a < -\frac{5}{2}

a > -\frac{5}{2}

a > \frac{5}{2}

a < \frac{5}{2}

Cevabı ve açıklamayı göster

Cevap: $a < -\frac{5}{2}$

Cevap

The value of

a

must satisfy

a < -\frac{5}{2}

.

To find the correct range for

a

, we first expand the inequality

5x - a(3 - 2x) \ge 4

using the distributive property, which yields

5x - 3a + 2ax \ge 4

. Grouping the

x

terms gives

(5 + 2a)x \ge 3a + 4

. The problem states that the solution set is of the form

x \le d

. Because the inequality sign flipped from greater-than-or-equal-to (

\ge

) to less-than-or-equal-to (

\le

), the coefficient of

x

must be negative. Setting the coefficient

5 + 2a < 0

and solving for

a

gives

a < -\frac{5}{2}

.

Adım Adım Çözüm

1

Expand the inequality to separate the terms.

5x - 3a + 2ax \ge 4

Apply the distributive property to the term

-a(3 - 2x)

, paying close attention to the signs:

-a \times 3 = -3a

and

-a \times (-2x) = 2ax

.

2

Group and factor the terms containing

x

on the left side, and move the constant terms to the right side.

(5 + 2a)x \ge 3a + 4

Factor out

x

from the terms

5x

and

2ax

to isolate the variable, and add

3a

to both sides of the inequality.

3

Analyze the relationship between the coefficient of

x

and the inequality sign of the solution set.

5 + 2a < 0

The original inequality has a greater-than-or-equal-to sign (

\ge

), but the given solution set is of the form

x \le d

(less-than-or-equal-to). For the inequality sign to reverse when dividing both sides by the coefficient of

x

, the coefficient

(5 + 2a)

must be negative.

4

Solve the inequality for

a

.

a < -\frac{5}{2}

Subtract 5 from both sides to get

2a < -5

, then divide both sides by 2.

Anahtar Kavram

Solving linear inequalities in one variable with symbolic coefficients and applying the inequality sign reversal rule when multiplying or dividing by a negative value.

Soru 16Soru →

In the inequality $3(4 - 2x) - 5(x - c) \geq -7$ , where $c$ is a constant, the solution set consists of all values of $x$ such that $x \leq 3$ . What is the value of $c$ ?

Cevabı ve açıklamayı göster

Cevap: 2.8

Cevap

2.8

To find the value of

c

, first simplify the inequality

3(4 - 2x) - 5(x - c) \geq -7

by expanding the terms using the distributive property, which yields

12 - 6x - 5x + 5c \geq -7

. Combining like terms gives

-11x + 12 + 5c \geq -7

. Next, isolate the variable term by subtracting

12

and

5c

from both sides to obtain

-11x \geq -19 - 5c

. Dividing both sides of the inequality by

-11

and reversing the inequality sign results in

x \leq \frac{19 + 5c}{11}

. Given that the solution set consists of all values of

x

such that

x \leq 3

, the boundary value

\frac{19 + 5c}{11}

must equal

3

. Solving the equation

\frac{19 + 5c}{11} = 3

gives

19 + 5c = 33

, which simplifies to

5c = 14

and results in

c = 2.8

.

Adım Adım Çözüm

1

Distribute the constants on the left side of the inequality.

12 - 6x - 5x + 5c \geq -7

Applying the distributive property simplifies the parentheses.

2

Combine the variable terms.

-11x + 12 + 5c \geq -7

Grouping like terms simplifies the inequality.

3

Subtract

12

and

5c

from both sides of the inequality.

-11x \geq -19 - 5c

This isolates the term containing

x

.

4

Divide both sides by

-11

and reverse the direction of the inequality.

x \leq \frac{19 + 5c}{11}

Dividing by a negative number requires flipping the inequality sign to maintain equivalence.

5

Set the algebraic boundary

\frac{19 + 5c}{11}

equal to the given boundary value of

3

and solve for

c

.

c = 2.8

Since the solution set is

x \leq 3

, the boundary values must be equivalent.

Anahtar Kavram

Solving multi-step linear inequalities in one variable containing parameters.

Soru 17Soru →

For a constant $k$ , the inequality $2(3 - x) - k(x + 5) > 4$ has the solution set $x < -3$ . What is the value of $k$ ?

-1

2

4

-0.5

Cevabı ve açıklamayı göster

Cevap: $4$

Cevap

4

The correct answer is

4

. Expanding the inequality

2(3 - x) - k(x + 5) > 4

gives

6 - 2x - kx - 5k > 4

. Grouping the

x

terms yields

(-2 - k)x > 5k - 2

. Because the given solution set is

x < -3

, the inequality sign must flip, indicating that the coefficient

-2 - k

is negative. Dividing by this negative coefficient yields

x < \frac{5k - 2}{-2 - k}

. Setting the boundary expression equal to the boundary of the solution set gives

\frac{5k - 2}{-2 - k} = -3

. Multiplying both sides by

-2 - k

results in

5k - 2 = 6 + 3k

. Subtracting

3k

and adding

2

to both sides gives

2k = 8

, which simplifies to

k = 4

.

Adım Adım Çözüm

1

Distribute the constants in the inequality

6 - 2x - kx - 5k > 4

To clear parentheses and prepare to group terms.

2

Group the

x

terms and constant terms

(-2 - k)x > 5k - 2

To isolate the variable

x

on one side of the inequality.

3

Divide by the coefficient of

x

and flip the inequality direction

x < \frac{5k - 2}{-2 - k}

Since the solution set is

x < -3

, the direction of the inequality must flip from

>

to

<

, meaning the coefficient

-2 - k

must be negative.

4

Set the boundary value equal to

-3

and solve for

k

k = 4

The boundary of the solution set must be equal to

-3

. Solving

\frac{5k - 2}{-2 - k} = -3

yields

5k - 2 = 6 + 3k

, which simplifies to

2k = 8

, so

k = 4

.

Anahtar Kavram

Solving linear inequalities in one variable with symbolic coefficients, accounting for direction flips when dividing by negative quantities.

Soru 18Soru →

A shipping container has a maximum weight capacity of $24,150$ kilograms. The container is loaded with $12$ machinery units, each weighing $1,150$ kilograms. The remaining space will be filled with packing crates, each weighing $180$ kilograms. A safety regulation requires that a clearance weight of at least $15\%$ of the total loaded weight (the combined weight of the machinery units and the packing crates) must be left unused. What is the maximum number of packing crates that can be loaded into the container?

Cevabı ve açıklamayı göster

Cevap: 40

Cevap

The maximum number of packing crates that can be loaded is 40.

By setting up the inequality representing the physical constraints, we find that the number of packing crates,

x

, must satisfy

x \le 40

. Since the question asks for the maximum number of packing crates, the maximum value is 40.

Adım Adım Çözüm

1

Calculate the constant weight of the machinery units.

The total weight of the

12

machinery units is

12 \times 1,150 = 13,800

kilograms.

This establishes the base weight that is already loaded in the container.

2

Define the variable and write the expression for the total loaded weight.

Let

x

be the number of packing crates. The total loaded weight is

13,800 + 180x

kilograms.

This represents the combined weight of the machinery and the crates in terms of the variable

x

.

3

Set up the inequality representing the safety clearance requirement.

24,150 - (13,800 + 180x) \ge 0.15(13,800 + 180x)

The unused weight capacity (maximum capacity minus loaded weight) must be at least

15\%

of the loaded weight.

4

Solve the inequality for

x

.

24,150 \ge 1.15(13,800 + 180x) \implies 21,000 \ge 13,800 + 180x \implies 7,200 \ge 180x \implies x \le 40

.

Isolating

x

gives the range of allowable values for the number of packing crates.

Anahtar Kavram

Formulating and solving linear inequalities in one variable based on real-world constraints.

Soru 19Soru →

A researcher is monitoring the temperature, $T$ , in degrees Celsius, of a chemical reaction. The target temperature range is maintained by an automated cooling system that activates when the temperature satisfies the inequality $-5(T - 12) - 8(3 - 2T) < 14(T + 3)$ . Which of the following inequalities represents all possible values of $T$ for which the cooling system will activate?

T < -2

T > -2

T > -42

T > 2

Cevabı ve açıklamayı göster

Cevap: $T > -2$

Cevap

The inequality representing all possible values of the temperature is

T > -2

.

The correct inequality is obtained by first expanding both sides of the inequality to get

-5T + 60 - 24 + 16T < 14T + 42

. Simplifying the left side yields

11T + 36 < 14T + 42

. Subtracting

14T

from both sides gives

-3T + 36 < 42

, and subtracting

36

from both sides gives

-3T < 6

. Finally, dividing both sides by

-3

and reversing the inequality sign results in

T > -2

.

Adım Adım Çözüm

1

Distribute the constants on both sides of the inequality:

-5(T - 12) - 8(3 - 2T) < 14(T + 3)

.

-5T + 60 - 24 + 16T < 14T + 42

Remove the parentheses to prepare the inequality for simplification.

2

Combine the like terms on the left side of the inequality.

11T + 36 < 14T + 42

Simplify the expression before isolating the variable.

3

Subtract

14T

and

36

from both sides of the inequality.

-3T < 6

Group all variable terms on one side and constant terms on the other.

4

Divide both sides of the inequality by

-3

and reverse the inequality sign.

T > -2

Dividing by a negative number reverses the inequality relationship.

Anahtar Kavram

Solving multi-step linear inequalities in one variable, distributing coefficients, combining like terms, and reversing the inequality sign when dividing by a negative number.

Tahmini Süre:2m 0s

Soru 20Soru →

The temperature, $T$ , in degrees Fahrenheit ( $^\circ\text{F}$ ), of a laboratory incubator $m$ minutes after a cooling cycle begins is modeled by the equation $T = 95 - 0.8(2m - 5)$ . For a specific experiment, the incubator temperature must be at most $75^\circ\text{F}$ . Which of the following inequalities represents all possible values of $m$ for which the incubator temperature meets this requirement?

m \geq 15

m \leq 15

m \geq 10

m \geq 30

Cevabı ve açıklamayı göster

Cevap: $m \geq 15$

Cevap

The correct inequality is

m \geq 15

.

The correct inequality is

m \geq 15

. To find this, set the temperature model

95 - 0.8(2m - 5)

to be less than or equal to

75

. Subtracting

95

from both sides gives

-0.8(2m - 5) \leq -20

. Dividing both sides by

-0.8

requires flipping the inequality sign, which yields

2m - 5 \geq 25

. Adding

5

to both sides gives

2m \geq 30

, and dividing by

2

yields

m \geq 15

.

Adım Adım Çözüm

1

Set up the inequality based on the requirement that the temperature must be at most

75^\circ\text{F}

.

95 - 0.8(2m - 5) \leq 75

The phrase 'at most' corresponds to a less-than-or-equal-to sign.

2

Subtract

95

from both sides of the inequality.

-0.8(2m - 5) \leq -20

This begins the process of isolating the term containing the variable

m

.

3

Divide both sides by

-0.8

and flip the inequality sign.

2m - 5 \geq 25

Dividing both sides of an inequality by a negative number requires reversing the direction of the inequality sign.

4

Add

5

to both sides of the inequality.

2m \geq 30

This isolates the variable term

2m

.

5

Divide both sides by

2

to solve for

m

.

m \geq 15

This yields the solution set for the variable

m

.

Anahtar Kavram

Solving multi-step linear inequalities in one variable, specifically expanding using the distributive property and reversing the inequality sign when multiplying or dividing by a negative number.

Linear Inequalities in One Variable

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