JAMB Mathematics Past Questions & Answers - Page 92

456.

Evaluate \(\int\limits_0^\frac{\pi}{2}\) sin xdx

A.

2

B.

-1

C.

1

D.

-2

Correct answer is C

\(\int\limits_0^\frac{\pi}{2}\) sin xdx = -cosx|\(\frac{\pi}{2}\)

= -(cos\(\frac{\pi}{2}\) - cos0) = -(0-1) = 1

457.

An arc subtends an angle of 30<sup>o</sup> at the centre of a circle radius 12cm. Calculate the length of the arc.

A.

6\(\pi\)cm

B.

2\(\pi\)cm

C.

3\(\pi\)cm

D.

9\(\pi\)cm

Correct answer is B

Length or arc = \(\frac{\theta}{360}\) x 2\(\pi\)r

= \(\frac{30}{360}\) x 2 x \(\frac{22}{7}\) x 12

= \(\frac{1}{12}\) x 2 x \(\pi\) x 2 = 2\(\pi\)cm

458.

Evaluate \(\frac{0.8 \times 0.43 \times 0.031}{0.05 \times 0.72 \times 0.021}\). Correct to four significant figures.

A.

14.09

B.

14.1

C.

14.12

D.

14.11

Correct answer is D

\(\frac{0.8 \times 0.43 \times 0.031}{0.05 \times 0.72 \times 0.021}\) x \(\frac{10}{10}\) = 14.11

459.

Find \(\frac{dy}{dx}\), if y = \(\frac{2}{3}\) x\(^3\) - \(\frac{4}{x}\)

A.

3x2 - \(\frac{4}{x}\)

B.

2x2 +\(\frac{4}{x^2}\)

C.

3x2 + \(\frac{4}{x^2}\)

D.

2x2 - \(\frac{4}{x}\)

Correct answer is B

No explanation has been provided for this answer.