Tüm alıştırma soruları

1526 soru

Soru 741Soru

The critical velocity vcv_c of a fluid flowing through a cylindrical pipe of diameter DD depends on the dynamic viscosity η\eta of the fluid, its density ρ\rho, and the pipe diameter DD according to the empirical relationship vc=ReηxρyDzv_c = R_e \eta^x \rho^y D^z, where ReR_e is the dimensionless Reynolds number. Using dimensional analysis, calculate the numerical value of the sum of the exponents x+y+zx + y + z.

Cevabı ve açıklamayı göster

Cevap: -1

Cevap

The sum of the exponents x+y+zx + y + z is 1-1.
Using the principle of dimensional homogeneity, the dimensions of both sides of the formula vc=ReηxρyDzv_c = R_e \eta^x \rho^y D^z must be equal. Equating the powers of Mass, Length, and Time yields x=1x = 1, y=1y = -1, and z=1z = -1. Summing these three values gives 1+(1)+(1)=11 + (-1) + (-1) = -1.

Adım Adım Çözüm

1
Determine the dimensions of all physical quantities involved
Critical velocity [vc]=L T1[v_c] = \text{L T}^{-1}, dynamic viscosity [η]=M L1T1[\eta] = \text{M L}^{-1} \text{T}^{-1}, fluid density [ρ]=M L3[\rho] = \text{M L}^{-3}, and diameter [D]=L[D] = \text{L}. The Reynolds number ReR_e is dimensionless.
Dimensional analysis requires replacing physical quantities with their base SI dimensions.
2
Formulate the dimensional homogeneity equation
\text{M}^0 \text{L}^1 \text{T}^{-1} = (\text{M L}^{-1} \text{T}^{-1})^x (\text{M L}^{-3})^y (\text{L})^z = \text{M}^{x+y} \text{L}^{-x-3y+z} \text{T}^{-x}.
By the principle of dimensional homogeneity, the total exponent of each fundamental dimension must match on both sides of the equation.
3
Solve the system of simultaneous linear equations for xx, yy, and zz
From T\text{T}: x=1    x=1-x = -1 \implies x = 1.
From M\text{M}: x+y=0    y=1x + y = 0 \implies y = -1.
From L\text{L}: x3y+z=1    1+3+z=1    z=1-x - 3y + z = 1 \implies -1 + 3 + z = 1 \implies z = -1.
Equating powers of fundamental quantities yields explicit values for each dimensional power.
4
Calculate the target sum x+y+zx + y + z
x + y + z = 1 + (-1) + (-1) = -1.
Combining the calculated exponents gives the required numerical value.

Anahtar Kavram

Principle of Dimensional Homogeneity and Derivation of Physical Formulas
Soru 742Soru

Given the simultaneous equations 2xy=42x - y = 4 and x2+y2=13x^2 + y^2 = 13, where both xx and yy are positive real numbers, calculate the value of x+yx + y.

Cevabı ve açıklamayı göster

Cevap: 5

Cevap

The correct value of x+yx + y is 5.
Substituting y=2x4y = 2x - 4 into x2+y2=13x^2 + y^2 = 13 gives 5x216x+3=05x^2 - 16x + 3 = 0, which yields x=3x = 3 or x=0.2x = 0.2. The corresponding yy-values are y=2y = 2 and y=3.6y = -3.6. Since both xx and yy must be positive, the valid pair is (3,2)(3, 2), giving x+y=3+2=5x + y = 3 + 2 = 5.

Adım Adım Çözüm

1
Express yy in terms of xx using the linear equation 2xy=42x - y = 4.
y=2x4y = 2x - 4
Substitution is the standard method for solving simultaneous linear and quadratic equations.
2
Substitute y=2x4y = 2x - 4 into the quadratic equation x2+y2=13x^2 + y^2 = 13.
x2+(2x4)2=13x^2 + (2x - 4)^2 = 13
This reduces the system to a single quadratic equation in one variable.
3
Expand and collect like terms.
5x216x+3=05x^2 - 16x + 3 = 0
Expanding (2x4)2=4x216x+16(2x - 4)^2 = 4x^2 - 16x + 16 and subtracting 13 puts the quadratic in standard form ax2+bx+c=0ax^2 + bx + c = 0.
4
Solve the quadratic equation 5x216x+3=05x^2 - 16x + 3 = 0 for xx.
x=3x = 3 or x=0.2x = 0.2
Factoring (5x1)(x3)=0(5x - 1)(x - 3) = 0 yields two real solutions for xx.
5
Find corresponding values of yy and apply the positivity constraint x>0x > 0 and y>0y > 0.
x=3,y=2x = 3, y = 2
When x=0.2x = 0.2, y=3.6y = -3.6, which is not positive. Hence, (3,2)(3, 2) is the only valid solution pair.
6
Calculate x+yx + y.
5
3+2=53 + 2 = 5.

Anahtar Kavram

Solving simultaneous linear and quadratic equations using substitution
Tahmini Süre:1m 30s
Soru 743Soru

A curve has a gradient function defined by dydx=12x36sin(3x)+4\frac{dy}{dx} = 12x^3 - 6\sin(3x) + 4. If the curve passes through the point (0,15)(0, 15), what is the value of the constant of integration CC?

Cevabı ve açıklamayı göster

Cevap: 13

Cevap

The constant of integration CC is 13.
Integrating 12x36sin(3x)+412x^3 - 6\sin(3x) + 4 with respect to xx yields y=3x4+2cos(3x)+4x+Cy = 3x^4 + 2\cos(3x) + 4x + C. Substituting x=0x = 0 and y=15y = 15 gives 15=3(0)4+2cos(0)+4(0)+C=2+C15 = 3(0)^4 + 2\cos(0) + 4(0) + C = 2 + C, which simplifies to C=13C = 13.

Adım Adım Çözüm

1
Integrate the gradient function to obtain the general equation of the curve.
y=3x4+2cos(3x)+4x+Cy = 3x^4 + 2\cos(3x) + 4x + C
The integral of 12x312x^3 is 3x43x^4, the integral of 6sin(3x)-6\sin(3x) is +2cos(3x)+2\cos(3x), and the integral of 44 is 4x4x.
2
Apply the initial condition (0,15)(0, 15) to solve for CC.
15=3(0)4+2cos(0)+4(0)+C15 = 3(0)^4 + 2\cos(0) + 4(0) + C
Substitute x=0x = 0 and y=15y = 15 into the integrated equation.
3
Calculate the numerical value of CC.
C=13C = 13
Since cos(0)=1\cos(0) = 1, the equation becomes 15=2+C15 = 2 + C, yielding C=13C = 13.

Anahtar Kavram

Indefinite Integration of Polynomial and Trigonometric Functions with Initial Conditions
Soru 744Soru

Given the matrices A=(x21302141)A = \begin{pmatrix} x & 2 & 1 \\ 3 & 0 & 2 \\ 1 & 4 & 1 \end{pmatrix} and B=(2153)B = \begin{pmatrix} 2 & -1 \\ 5 & 3 \end{pmatrix}, find the value of xx if det(A)+det(B)=5\det(A) + \det(B) = 5.

Cevabı ve açıklamayı göster

Cevap: 2

Cevap

The value of x is 2.
Evaluating \det(B) gives 11, and cofactor expansion of \det(A) along the top row yields 10 - 8x. Summing these determinants gives (10 - 8x) + 11 = 5, which simplifies to 8x = 16, resulting in x = 2.

Adım Adım Çözüm

1
Calculate the determinant of the 2x2 matrix B
\det(B) = 11
For a 2x2 matrix \begin{pmatrix} a & b \\ c & d \end{pmatrix}, the determinant is ad - bc. Thus, \det(B) = (2)(3) - (-1)(5) = 6 + 5 = 11.
2
Calculate the determinant of the 3x3 matrix A in terms of x
\det(A) = 10 - 8x
Expanding along the first row: \det(A) = x\begin{vmatrix} 0 & 2 \\ 4 & 1 \end{vmatrix} - 2\begin{vmatrix} 3 & 2 \\ 1 & 1 \end{vmatrix} + 1\begin{vmatrix} 3 & 0 \\ 1 & 4 \end{vmatrix} = x(0 - 8) - 2(3 - 2) + 1(12 - 0) = -8x - 2 + 12 = 10 - 8x.
3
Set up and solve the linear equation \det(A) + \det(B) = 5
x = 2
Substituting the computed determinants gives (10 - 8x) + 11 = 5, which simplifies to 21 - 8x = 5. Rearranging yields 8x = 16, so x = 2.

Anahtar Kavram

Determinants of 2x2 and 3x3 matrices and linear equation solving
Soru 745Soru

A small charged sphere of mass 2.0×104 kg2.0 \times 10^{-4}\text{ kg} carrying a positive charge of +4.0×108 C+4.0 \times 10^{-8}\text{ C} is suspended by a light insulating string between two vertical parallel plates. When a uniform horizontal electric field of magnitude EE is applied between the plates, the string deflects and comes to equilibrium at an angle of 4545^\circ to the vertical. Taking the acceleration due to gravity g=10 ms2g = 10\text{ m}\cdot\text{s}^{-2}, calculate the magnitude of the electric field intensity EE in NC1\text{N}\cdot\text{C}^{-1}.

Cevabı ve açıklamayı göster

Cevap: 50000

Cevap

The magnitude of the electric field intensity is 50000 NC150000\text{ N}\cdot\text{C}^{-1} (or 5.0×104 NC15.0 \times 10^4\text{ N}\cdot\text{C}^{-1}).
In electrostatic equilibrium, the sphere experiences three forces: weight (mgmg) vertically downward, electrostatic force (qEqE) horizontally, and tension (TT) along the thread at 4545^\circ to the vertical. Balancing components gives Tsin45=qET \sin 45^\circ = qE and Tcos45=mgT \cos 45^\circ = mg. Dividing these yields tan45=qEmg=1\tan 45^\circ = \frac{qE}{mg} = 1, which gives qE=mgqE = mg. Substituting the given values gives E=2.0×1034.0×108=50000 NC1E = \frac{2.0 \times 10^{-3}}{4.0 \times 10^{-8}} = 50000\text{ N}\cdot\text{C}^{-1}.

Adım Adım Çözüm

1
Calculate the weight of the charged sphere.
W=mg=(2.0×104 kg)(10 ms2)=2.0×103 NW = mg = (2.0 \times 10^{-4}\text{ kg})(10\text{ m}\cdot\text{s}^{-2}) = 2.0 \times 10^{-3}\text{ N}.
The weight provides the downward vertical force in equilibrium.
2
Relate the electrostatic force to the weight using the angle of deflection.
tan(45)=FeW    1=Fe2.0×103 N    Fe=2.0×103 N\tan(45^\circ) = \frac{F_e}{W} \implies 1 = \frac{F_e}{2.0 \times 10^{-3}\text{ N}} \implies F_e = 2.0 \times 10^{-3}\text{ N}.
In electrostatic equilibrium, the ratio of the horizontal force to the vertical force equals the tangent of the angle with the vertical.
3
Calculate the electric field strength EE using Fe=qEF_e = qE.
E=Feq=2.0×103 N4.0×108 C=50000 NC1E = \frac{F_e}{q} = \frac{2.0 \times 10^{-3}\text{ N}}{4.0 \times 10^{-8}\text{ C}} = 50000\text{ N}\cdot\text{C}^{-1}.
The electric field intensity is the electric force per unit charge.

Anahtar Kavram

Equilibrium of a charged body in a uniform electric field
Tahmini Süre:2m 0s
Soru 746Soru

A trader bought a set of solar panels for 160,000\text{₦}160,000. He marked up the cost price by 25%25\% to fix the marked price. During a trade fair, he offered a 10%10\% discount on the marked price. What is his net profit in Naira?

Cevabı ve açıklamayı göster

Cevap: 20000

Cevap

The net profit made by the trader is ���20,000.
First, find the marked price by adding a 25% markup to the cost price: ₦160,000 × 1.25 = ₦200,000. Next, calculate the selling price after a 10% discount on the marked price: ₦200,000 × 0.90 = ₦180,000. Finally, subtract the cost price from the selling price to find the net profit: ₦180,000 - ₦160,000 = ₦20,000.

Adım Adım Çözüm

1
Calculate the marked price
Marked Price = ₦200,000
The marked price is 125% of the original cost price of ₦160,000.
2
Calculate the selling price after discount
Selling Price = ₦180,000
A 10% discount reduces the marked price by ₦20,000.
3
Determine the net profit
Net Profit = ₦20,000
Net profit is the difference between the selling price (₦180,000) and the cost price (₦160,000).

Anahtar Kavram

Markup, Discount, and Profit Calculations
Soru 747Soru

A pie chart illustrates the annual allocation of funds for an agricultural research station across four sectors: Crop Research, Livestock, Irrigation, and Equipment Maintenance. The sector angles for Crop Research, Livestock, and Irrigation are 135135^\circ, 9090^\circ, and 6060^\circ respectively. If the total annual budget is N7,200,000\text{N}7,200,000, what is the amount allocated to Equipment Maintenance in Naira?

Cevabı ve açıklamayı göster

Cevap: 1500000

Cevap

The amount allocated to Equipment Maintenance is 1,500,000 Naira.
A complete pie chart has a total angle of 360360^\circ, representing the full amount of N7,200,000\text{N}7,200,000. The angle corresponding to Equipment Maintenance is 360(135+90+60)=75360^\circ - (135^\circ + 90^\circ + 60^\circ) = 75^\circ. The dollar/naira allocation is given by 75360×7,200,000=1,500,000\frac{75^\circ}{360^\circ} \times 7,200,000 = 1,500,000.

Adım Adım Çözüm

1
Calculate the sum of the given sector angles
Sum of known angles = 285 degrees
Determining the total angular measure already accounted for by the three known sectors.
2
Subtract the sum of known angles from 360 degrees
Sector angle for Equipment Maintenance = 75 degrees
The sum of all sector angles in a pie chart is always 360 degrees.
3
Multiply the fraction of the pie chart by the total funds
1,500,000 Naira
Converting the sector angle representation to its corresponding quantitative value.

Anahtar Kavram

Pie chart sector angle computation and value conversion
Soru 748Soru

In a hydrogen atom modeled according to Bohr's theory, an electron undergoes a transition from an excited state with an energy of 1.51 eV-1.51\text{ eV} to a lower energy state of 3.40 eV-3.40\text{ eV}. Calculate the energy of the emitted photon in electron-volts (eV\text{eV}).

Cevabı ve açıklamayı göster

Cevap: 1.89

Cevap

The energy of the emitted photon is 1.89 eV1.89\text{ eV}.
According to Bohr's atomic model, when an electron drops from an initial higher energy level EiE_i to a final lower energy level EfE_f, a photon is emitted carrying energy E=EiEfE = E_i - E_f. Substituting the given values gives E=1.51 eV(3.40 eV)=1.89 eVE = -1.51\text{ eV} - (-3.40\text{ eV}) = 1.89\text{ eV}.

Adım Adım Çözüm

1
Identify the initial and final energy states of the electron.
Ei=1.51 eVE_i = -1.51\text{ eV} and Ef=3.40 eVE_f = -3.40\text{ eV}.
The electron moves from a higher (less negative) energy state to a lower (more negative) energy state.
2
Apply Bohr's energy quantization formula for photon emission Ephoton=EiEfE_{\text{photon}} = E_i - E_f.
Ephoton=1.51(3.40)=1.89 eVE_{\text{photon}} = -1.51 - (-3.40) = 1.89\text{ eV}.
By energy conservation, the energy lost by the transitioning electron equals the energy of the emitted photon.

Anahtar Kavram

Bohr's Energy Transition Postulate
Tahmini Süre:1m 0s
Soru 749Soru

A binary operation \star on the set of real numbers R{1}\mathbb{R} \setminus \{1\} is defined by ab=a+baba \star b = a + b - ab. If y1y^{-1} denotes the inverse of an element yy under \star, find the value of xx such that (x3)1=2(x \star 3)^{-1} = 2.

Cevabı ve açıklamayı göster

Cevap: 0.5

Cevap

The value of xx is 0.50.5.
To solve for xx, first calculate the identity element e=0e = 0 using ae=aa \star e = a. Next, use yy1=0y \star y^{-1} = 0 to get the inverse formula y1=yy1y^{-1} = \frac{y}{y - 1}. Substituting y=x3=32xy = x \star 3 = 3 - 2x into the inverse formula yields 32x22x=2\frac{3 - 2x}{2 - 2x} = 2, which simplifies to 2x=12x = 1, giving x=0.5x = 0.5.

Adım Adım Çözüm

1
Find the identity element ee of the operation \star.
e=0e = 0
By definition of the identity element, ae=a    a+eae=a    e(1a)=0a \star e = a \implies a + e - ae = a \implies e(1 - a) = 0, so e=0e = 0 for all a1a \neq 1.
2
Derive the general expression for the inverse element y1y^{-1} of yy.
y1=yy1y^{-1} = \frac{y}{y - 1}
By definition of inverse element, yy1=e    y+y1yy1=0    y1(1y)=y    y1=yy1y \star y^{-1} = e \implies y + y^{-1} - y y^{-1} = 0 \implies y^{-1}(1 - y) = -y \implies y^{-1} = \frac{y}{y - 1}.
3
Evaluate the inner operation x3x \star 3.
x3=32xx \star 3 = 3 - 2x
Using the operational rule ab=a+baba \star b = a + b - ab, we obtain x3=x+33x=32xx \star 3 = x + 3 - 3x = 3 - 2x.
4
Set up and solve the equation (x3)1=2(x \star 3)^{-1} = 2.
x=0.5x = 0.5
Letting y=32xy = 3 - 2x, its inverse is y1=32x(32x)1=32x22xy^{-1} = \frac{3 - 2x}{(3 - 2x) - 1} = \frac{3 - 2x}{2 - 2x}. Equating this to 22 gives 32x22x=2    32x=44x    2x=1    x=0.5\frac{3 - 2x}{2 - 2x} = 2 \implies 3 - 2x = 4 - 4x \implies 2x = 1 \implies x = 0.5.

Anahtar Kavram

Identity and Inverse Elements in Binary Operations
Soru 750Soru

A binary operation \oplus is defined on the set of real numbers R\mathbb{R} by ab=2a+3b5a \oplus b = 2a + 3b - 5. What is the value of (41)2(4 \oplus 1) \oplus 2?

Cevabı ve açıklamayı göster

Cevap: 13

Cevap

The value of (41)2(4 \oplus 1) \oplus 2 is 13.
First, evaluate the inner expression 414 \oplus 1 using a=4a = 4 and b=1b = 1, which gives 2(4)+3(1)5=8+35=62(4) + 3(1) - 5 = 8 + 3 - 5 = 6. Then, substitute this result into the outer expression to evaluate 626 \oplus 2 using a=6a = 6 and b=2b = 2, yielding 2(6)+3(2)5=12+65=132(6) + 3(2) - 5 = 12 + 6 - 5 = 13.

Adım Adım Çözüm

1
Evaluate the inner operation 414 \oplus 1
6
Substitute a=4a = 4 and b=1b = 1 into the operational rule ab=2a+3b5a \oplus b = 2a + 3b - 5.
2
Evaluate the outer operation using the result from Step 1: 626 \oplus 2
13
Substitute a=6a = 6 and b=2b = 2 into the operational rule ab=2a+3b5a \oplus b = 2a + 3b - 5.

Anahtar Kavram

Evaluation of Binary Operations
Soru 751Soru

If 52x1×25x+1=125x+25^{2x - 1} \times 25^{x + 1} = 125^{x + 2}, what is the value of xx?

Cevabı ve açıklamayı göster

Cevap: 5

Cevap

The value of xx is 55.
Converting all terms to base 55 gives 52x1×52(x+1)=53(x+2)5^{2x - 1} \times 5^{2(x + 1)} = 5^{3(x + 2)}. Simplifying the exponents yields 52x1+2x+2=53x+65^{2x - 1 + 2x + 2} = 5^{3x + 6}, which reduces to 54x+1=53x+65^{4x + 1} = 5^{3x + 6}. Setting the exponents equal to each other gives 4x+1=3x+64x + 1 = 3x + 6, resulting in x=5x = 5.

Adım Adım Çözüm

1
Express all bases in terms of prime base 5
52x1×(52)x+1=(53)x+25^{2x - 1} \times (5^2)^{x + 1} = (5^3)^{x + 2}
All terms must share the same base to combine exponents using index laws.
2
Apply power of a power rule (am)n=amn(a^m)^n = a^{mn}
52x1×52x+2=53x+65^{2x - 1} \times 5^{2x + 2} = 5^{3x + 6}
Multiplication of inner and outer powers simplifies composite exponent expressions.
3
Apply the product rule am×an=am+na^m \times a^n = a^{m+n}
54x+1=53x+65^{4x + 1} = 5^{3x + 6}
Adding the exponents on the left-hand side produces a single exponential term.
4
Equate exponents and solve for xx
x=5x = 5
Equal bases imply equal exponents: 4x+1=3x+64x + 1 = 3x + 6.

Anahtar Kavram

Solving exponential equations using common base conversion and laws of indices
Tahmini Süre:1m 30s
Soru 752Soru

A plane contains 1212 distinct points such that exactly 55 of them lie on the same straight line, while no other subset of three points is collinear. How many distinct straight lines can be formed by joining pairs of these points?

Cevabı ve açıklamayı göster

Cevap: 57

Cevap

The total number of distinct straight lines that can be formed is 57.
The total number of distinct straight lines is obtained by taking all possible pairs of points from 12, which is 12C2=66^{12}C_2 = 66, subtracting the pairs formed among the 5 collinear points (5C2=10^5C_2 = 10), and adding 1 back to account for the single straight line on which those 5 points lie. This gives 6610+1=5766 - 10 + 1 = 57.

Adım Adım Çözüm

1
Calculate the total possible lines by selecting any 2 points out of 12.
12C2=12×112=66^{12}C_2 = \frac{12 \times 11}{2} = 66
Any pair of non-collinear points uniquely determines a straight line.
2
Calculate the combinations of 2 points selected from the 5 collinear points.
5C2=5×42=10^5C_2 = \frac{5 \times 4}{2} = 10
These 10 point pairs all lie on the exact same single straight line instead of forming 10 distinct lines.
3
Adjust the count to find the net number of distinct straight lines.
6610+1=5766 - 10 + 1 = 57
Subtracting the 10 overcounted combinations and adding back 1 for the single line passing through all 5 collinear points gives the correct total.

Anahtar Kavram

Combinations with Collinear Constraints
Soru 753Soru

A search-and-rescue helicopter leaves a central station PP and flies 16 km16\text{ km} on a bearing of 050050^\circ to reach a waypoint QQ. It then changes course and flies 12 km12\text{ km} on a bearing of 140140^\circ to reach a mountain rescue site RR. From the central station PP, the angle of elevation to the helicopter hovering vertically above point RR is 4545^\circ. What is the vertical height of the helicopter above the horizontal plane of station PP, in kilometers?

Cevabı ve açıklamayı göster

Cevap: 20

Cevap

The vertical height of the helicopter above the horizontal plane of station PP is 20 km20\text{ km}.
The horizontal journey forms a right-angled triangle PQRPQR with side lengths 16 km16\text{ km} and 12 km12\text{ km}, yielding a hypotenuse (horizontal distance PRPR) of 20 km20\text{ km}. Since the angle of elevation from PP to the hovering helicopter is 4545^\circ, the vertical height is equal to 20×tan(45)=20 km20 \times \tan(45^\circ) = 20\text{ km}.

Adım Adım Çözüm

1
Find the back bearing of station PP from waypoint QQ
Back bearing = 050+180=230050^\circ + 180^\circ = 230^\circ
To determine the enclosed interior angle at point QQ, the reverse direction from QQ to PP must be calculated.
2
Calculate the interior angle PQR\angle PQR
\angle PQR = 230^\circ - 140^\circ = 90^\circ
Subtracting the forward bearing of RR from the back bearing of PP yields the right angle between the two paths.
3
Calculate the horizontal displacement distance PRPR
PR = \sqrt{16^2 + 12^2} = 20\text{ km}
Since PQR\triangle PQR is right-angled at QQ, the distance PRPR is obtained using the Pythagorean theorem.
4
Determine the vertical altitude using trigonometry
\text{Height} = PR \times \tan(45^\circ) = 20 \times 1 = 20\text{ km}
In the vertical right-angled triangle formed by PP, the ground projection of RR, and the helicopter, tan(45)=HeightHorizontal Distance\tan(45^\circ) = \frac{\text{Height}}{\text{Horizontal Distance}}.

Anahtar Kavram

Combining 3-point bearings in 2D with right-triangle trigonometry for 3D angles of elevation.
Soru 754Soru

What is the value of yy at the local minimum stationary point of the curve y=x33x29x+15y = x^3 - 3x^2 - 9x + 15 for x>0x > 0?

Cevabı ve açıklamayı göster

Cevap: -12

Cevap

The value of yy at the local minimum stationary point is 12-12.
To find the local minimum point of y=x33x29x+15y = x^3 - 3x^2 - 9x + 15, set the derivative dydx=3x26x9\frac{dy}{dx} = 3x^2 - 6x - 9 equal to 00. Solving 3(x3)(x+1)=03(x - 3)(x + 1) = 0 yields x=3x = 3 for x>0x > 0. The second derivative d2ydx2=6x6\frac{d^2y}{dx^2} = 6x - 6 equals 12>012 > 0 at x=3x = 3, confirming a local minimum. Substituting x=3x = 3 back into the original curve equation yields y=(3)33(3)29(3)+15=12y = (3)^3 - 3(3)^2 - 9(3) + 15 = -12.

Adım Adım Çözüm

1
Differentiate y=x33x29x+15y = x^3 - 3x^2 - 9x + 15 with respect to xx
\frac{dy}{dx} = 3x^2 - 6x - 9
Stationary points occur where the slope (first derivative) is zero.
2
Set dydx=0\frac{dy}{dx} = 0 and solve for xx
x = 3 \text{ or } x = -1
Factoring 3(x22x3)=03(x^2 - 2x - 3) = 0 gives (x3)(x+1)=0(x - 3)(x + 1) = 0.
3
Apply the second derivative test at x=3x = 3 (since x>0x > 0)
\frac{d^2y}{dx^2} = 6(3) - 6 = 12 > 0
A positive second derivative confirms that x=3x = 3 is a local minimum.
4
Evaluate yy at x=3x = 3 in the original curve equation
y = (3)^3 - 3(3)^2 - 9(3) + 15 = -12
Substituting x=3x = 3 into y(x)y(x) gives the yy-coordinate of the minimum point.

Anahtar Kavram

Stationary Points and Local Minima of Polynomial Curves
Soru 755Soru

If y=(4x32sin(x))dxy = \int (4x^3 - 2\sin(x)) \, dx and y=5y = 5 when x=0x = 0, what is the value of the constant of integration CC?

Cevabı ve açıklamayı göster

Cevap: 3

Cevap

The constant of integration CC is 3.
Integrating 4x32sin(x)4x^3 - 2\sin(x) gives y=x4+2cos(x)+Cy = x^4 + 2\cos(x) + C. Substituting x=0x = 0 and y=5y = 5 yields 5=0+2(1)+C5 = 0 + 2(1) + C, so C=3C = 3.

Adım Adım Çözüm

1
Integrate the polynomial and trigonometric terms
y=x4+2cos(x)+Cy = x^4 + 2\cos(x) + C
The integral of 4x34x^3 with respect to xx is x4x^4, and the integral of 2sin(x)-2\sin(x) is 2cos(x)2\cos(x).
2
Apply the given initial condition y(0)=5y(0) = 5
5=04+2cos(0)+C    5=2+C5 = 0^4 + 2\cos(0) + C \implies 5 = 2 + C
Evaluating the expression at x=0x = 0 uses the trigonometric property cos(0)=1\cos(0) = 1.
3
Solve the linear equation for CC
C=3C = 3
Subtracting 2 from both sides isolates CC.

Anahtar Kavram

Determining the Constant of Integration from Initial Boundary Conditions
Soru 756Soru

A biased four-sided die numbered 11, 22, 33, and 44 is rolled 200200 times in a probability experiment. The frequency of each outcome is recorded in the table below:

OutcomeFrequency
114545
226060
335555
444040

What is the experimental probability of rolling an odd number?

Cevabı ve açıklamayı göster

Cevap: 0.5

Cevap

0.5
The correct experimental probability is calculated by dividing the total frequency of observed odd outcomes (45+55=10045 + 55 = 100) by the total number of trials (200200), which gives 100200=0.5\frac{100}{200} = 0.5.

Adım Adım Çözüm

1
Identify the favorable outcomes for rolling an odd number
The odd outcomes on the die are 11 and 33.
Odd numbers are integers that are not divisible by 22.
2
Calculate the total frequency of the favorable outcomes
Frequency of 11 is 4545 and frequency of 33 is 5555. Total frequency =45+55=100= 45 + 55 = 100.
The total number of times an odd number was rolled is the sum of the frequencies of outcome 11 and outcome 33.
3
Compute the experimental probability
Experimental Probability=Frequency of odd outcomesTotal number of trials=100200=0.5\text{Experimental Probability} = \frac{\text{Frequency of odd outcomes}}{\text{Total number of trials}} = \frac{100}{200} = 0.5.
Experimental probability measures the relative frequency of an event occurring in an actual experiment.

Anahtar Kavram

Experimental Probability
Soru 757Soru

Find the sum of all values of xx (in degrees) in the interval 0x1800^\circ \le x \le 180^\circ that satisfy the trigonometric equation cos(3x45)=22\cos(3x - 45^\circ) = -\frac{\sqrt{2}}{2}.

Cevabı ve açıklamayı göster

Cevap: 330

Cevap

The sum of all values of xx satisfying the equation in the domain 0x1800^\circ \le x \le 180^\circ is 330.
Transforming the domain 0x1800^\circ \le x \le 180^\circ gives 453x45495-45^\circ \le 3x - 45^\circ \le 495^\circ. The angles within this range where the cosine value equals 22-\frac{\sqrt{2}}{2} are 135135^\circ, 225225^\circ, and 495495^\circ. Solving 3x453x - 45^\circ for each of these angles gives x=60x = 60^\circ, 9090^\circ, and 180180^\circ. Summing these three roots yields 330330^\circ.

Adım Adım Çözüm

1
Determine the interval of the transformed angle θ=3x45\theta = 3x - 45^\circ.
453x45495-45^\circ \le 3x - 45^\circ \le 495^\circ
Applying the linear transformation 3x453x - 45^\circ to the given domain 0x1800^\circ \le x \le 180^\circ establishes the exact boundaries for the argument of the cosine function.
2
Find all values of θ\theta within [45,495][-45^\circ, 495^\circ] satisfying cosθ=22\cos \theta = -\frac{\sqrt{2}}{2}.
θ{135,225,495}\theta \in \{135^\circ, 225^\circ, 495^\circ\}
Cosine is negative in Quadrants II and III. The reference angle is 4545^\circ, giving base solutions 135135^\circ and 225225^\circ. Adding 360360^\circ to 135135^\circ gives 495495^\circ, which lies exactly on the upper boundary.
3
Solve for xx by setting 3x453x - 45^\circ equal to each valid θ\theta.
x{60,90,180}x \in \{60^\circ, 90^\circ, 180^\circ\}
Isolating xx yields x=θ+453x = \frac{\theta + 45^\circ}{3}. All three resulting values lie within [0,180][0^\circ, 180^\circ].
4
Sum the valid solution values.
60^\circ + 90^\circ + 180^\circ = 330^\circ
The problem asks specifically for the sum of all solution angles in degrees.

Anahtar Kavram

Solving multi-angle trigonometric equations with phase shifts across a specified domain
Soru 758Soru

If xx and yy satisfy the simultaneous equations x2y=1x - 2y = 1 and x2xyy2=5x^2 - xy - y^2 = 5, what is the positive value of xx?

Cevabı ve açıklamayı göster

Cevap: 3

Cevap

The positive value of xx is 3.
Substituting x=2y+1x = 2y + 1 into the non-linear equation yields (2y+1)2(2y+1)yy2=5(2y + 1)^2 - (2y + 1)y - y^2 = 5, which simplifies to y2+3y4=0y^2 + 3y - 4 = 0. Solving this gives y=1y = 1 or y=4y = -4. Substituting y=1y = 1 into x=2y+1x = 2y + 1 gives x=3x = 3, which is the positive value of xx.

Adım Adım Çözüm

1
Make xx the subject of the linear equation
x=2y+1x = 2y + 1
Substitution is the standard method for solving linear-quadratic simultaneous systems.
2
Substitute x=2y+1x = 2y + 1 into x2xyy2=5x^2 - xy - y^2 = 5
(2y+1)2(2y+1)yy2=5(2y + 1)^2 - (2y + 1)y - y^2 = 5
Eliminates xx to create a single quadratic equation in terms of yy.
3
Expand and simplify to standard quadratic form
y2+3y4=0y^2 + 3y - 4 = 0
Simplifying algebraic expressions allows factorization.
4
Solve for yy by factoring
y=1y = 1 or y=4y = -4
Factors of 4-4 that sum to 33 are +4+4 and 1-1.
5
Calculate corresponding values for xx
x=3x = 3 when y=1y = 1, and x=7x = -7 when y=4y = -4
Substitute yy back into the linear expression for xx.
6
Select the positive value of xx
3
The question explicitly asks for the positive value of xx.

Anahtar Kavram

Simultaneous Linear and Quadratic Equations
Soru 759Soru

A solid rectangular wooden block measures 10 cm10\text{ cm} by 14 cm14\text{ cm} by 12 cm12\text{ cm}. A cylindrical hole of radius 3.5 cm3.5\text{ cm} is drilled straight through the block along its height of 12 cm12\text{ cm}. Taking π=227\pi = \frac{22}{7}, what is the volume of the remaining solid in cm3\text{cm}^3?

Cevabı ve açıklamayı göster

Cevap: 1218

Cevap

The volume of the remaining solid is 1218 cm31218\text{ cm}^3.
The initial total volume of the rectangular block is 10×14×12=1680 cm310 \times 14 \times 12 = 1680\text{ cm}^3. The volume of the cylindrical hole drilled through it is 227×(3.5)2×12=462 cm3\frac{22}{7} \times (3.5)^2 \times 12 = 462\text{ cm}^3. Subtracting the removed cylindrical volume from the block gives 1680462=1218 cm31680 - 462 = 1218\text{ cm}^3.

Adım Adım Çözüm

1
Calculate the total volume of the rectangular block.
Volume of block = 1680 cm31680\text{ cm}^3
The initial volume of the cuboid before drilling is calculated by multiplying its length, width, and height: 10×14×12=1680 cm310 \times 14 \times 12 = 1680\text{ cm}^3.
2
Calculate the volume of the cylindrical hole removed from the block.
Volume of cylinder = 462 cm3462\text{ cm}^3
The cylindrical hole has radius r=3.5 cm=72 cmr = 3.5\text{ cm} = \frac{7}{2}\text{ cm} and height h=12 cmh = 12\text{ cm}. Using V=πr2hV = \pi r^2 h, we get 227×494×12=462 cm3\frac{22}{7} \times \frac{49}{4} \times 12 = 462\text{ cm}^3.
3
Subtract the volume of the cylindrical hole from the total volume of the block.
Remaining volume = 1218 cm31218\text{ cm}^3
Because material is removed by drilling, the remaining volume is 1680462=1218 cm31680 - 462 = 1218\text{ cm}^3.

Anahtar Kavram

Volume of a composite solid (cuboid with a cylindrical cavity)
Soru 760Soru

What is the period, in degrees, of the trigonometric function y=7sin(5x)2y = 7\sin(5x) - 2?

Cevabı ve açıklamayı göster

Cevap: 72

Cevap

The period of the trigonometric function is 72 degrees.
For any function of the form y=Asin(Bx)+Dy = A\sin(Bx) + D, the period TT in degrees is calculated using T=360BT = \frac{360^\circ}{|B|}. For the given equation y=7sin(5x)2y = 7\sin(5x) - 2, the value of BB is 5. Substituting this into the formula gives T=3605=72T = \frac{360^\circ}{5} = 72^\circ.

Adım Adım Çözüm

1
Identify the coefficient BB of the variable xx in the given function y=7sin(5x)2y = 7\sin(5x) - 2.
Here, A=7A = 7, B=5B = 5, and D=2D = -2.
The period of a sine function depends on the angular frequency parameter BB multiplying the input variable xx.
2
Apply the standard formula for finding the period TT of a sine function in degrees: T=360BT = \frac{360^\circ}{|B|}.
T=3605=72T = \frac{360^\circ}{5} = 72^\circ.
Dividing the standard full revolution of 360360^\circ by the multiplier 55 determines the angle needed for one full cycle.

Anahtar Kavram

Period of a Trigonometric Graph
Tahmini Süre:45s
ÖncekiSayfa 38 / 77Sonraki
Tüm alıştırma soruları — JAMB UTME | Examkin