JAMB Mathematics Past Questions & Answers - Page 293

1,461.

If \(y = x(x^4 + x + 1)\), evaluate \(\int \limits_{0} ^{1} y \mathrm d x\).

A.

\(\frac{11}{12}\)

B.

1

C.

\(\frac{5}{6}\)

D.

zero

Correct answer is B

\(y = x(x^{4} + x + 1) = x^{5} + x^{2} + x\)

\(\int \limits_{0} ^{1} (x^{5} + x^{2} + x) \mathrm d x = \frac{x^{6}}{6} + \frac{x^{3}}{3} + \frac{x^{2}}{2}\)

= \([\frac{x^{6}}{6} + \frac{x^{3}}{3} + \frac{x^{2}}{2}]_{0} ^{1}\)

= \(\frac{1}{6} + \frac{1}{3} + \frac{1}{2}\)

= \(1\)

1,462.

Integrate \(\frac{1}{x}\) + cos x with respect to x

A.

-\(\frac{1}{x^2}\) + sin x + k

B.

x + sin x - k

C.

x - sin x + k

D.

-\(\frac{1}{x^2}\) - sin x + k

Correct answer is C

\(\int \frac{1}{x} + \cos x = ln x - \sin x + k\)

1,463.

\(\frac{d}{dx}\) cos(3x\(^2\) - 2x) is equal to

A.

-sin(6x - 2)

B.

-sin(3x2 - 2x)dx

C.

(6x - 2) sin(3x2 - 2x)

D.

-(6x - 2)sin(3x2 - 2x)

Correct answer is D

Let \(3x^{2} - 2x = u\)

\(y = \cos u \implies \frac{\mathrm d y}{\mathrm d u} = - \sin u\)

\(\frac{\mathrm d u}{\mathrm d x} = 6x - 2\)

\(\therefore \frac{\mathrm d y}{\mathrm d x} = (6x - 2) . - \sin u\)

= \(- (6x - 2) \sin (3x^{2} - 2x)\)

1,464.

Differentiate \(\frac{6x^3 - 5x^2 + 1}{3x^2}\) with respect to x

A.

\(\frac{2 + 2}{3x^3}\)

B.

2 + \(\frac{1}{6x}\)

C.

2 - \(\frac{2}{3x^3}\)

D.

\(\frac{1}{5}\)

Correct answer is C

\(\frac{6x^3 - 5x^2 + 1}{3x^2}\)

let y = 3x2

y = \(\frac{6x^3}{3x^2}\) - \(\frac{6x^2}{3x^2}\) + \(\frac{1}{3x^2}\)

Y = 2x - \(\frac{5}{3}\) + \(\frac{1}{3x^2}\)

\(\frac{dy}{dx}\) = 2 + \(\frac{1}{3}\)(-2)x-3

= 2 - \(\frac{2}{3x^3}\)

1,465.

In a triangle XYZ, if < ZYZ is 60, XY = 3cm and YZ = 4cm, calculate the length of the sides XZ.

A.

√23cm

B.

√13cm

C.

2√5cm

D.

2√3cm

Correct answer is B

(XZ)2 = 32 + 42 - 2 x 3 x 4 cos60o

= 25 - 24\(\frac{1}{2}\)

XZ = √13cm