WAEC Mathematics Past Questions & Answers - Page 61

301.

Find  the \(n^{th}\) term of the sequence 2 x 3, 4 x 6, 8 x 9, 16 x 12...

A.

2\(^n\) x 3(n + 1)

B.

2\(^n\) x 3n

C.

2\(^n\) x 3\(^n\)

D.

2\(^n\) x 3\(^n - 1\)

Correct answer is B

2 x 3, 4 x 6, 8 x 9, 16 x 12,...

2\(^1\) x 3 x 1, 2\(^2\) x 3 x 2, 2\(^3\) x 3 x 3, 2\(^4\) x 3 x 4,.... 2\(^n\) x 3n

302.

A.

(3x + 2)(1 - x)

B.

(3x + 2)(2x + 1)

C.

3\((x + 2)^2\)

D.

3(x + 1)(1 - x)

Correct answer is D

\((x + 2)^2\) - \((2x + 1)^2\)

= \((x^2 + 4x + 4) - (4x^2 + 4x + 1)\)

= \(x^2 \) + 4x + 4 - 4 \(x^2 \) - 4x - 1

= -3 \(x^2 \) + 3

= 3 - 3 \(x^2 \)

= 3(1 - \(x^2 \))

= 3(1 + x)(1 - x)

303.

Solved the equation \(2x^2 - x - 6\) = 0

A.

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

B.

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

C.

x = -3 or 2

D.

x = 3 or -2

Correct answer is A

\(2x^2 - x - 6\) = 0

\(2x^2 - 4x + 3x - 6\) = 0

2x(x - 2) + 3(x - 2) = 0

(2x + 3) (x - 2) = 0

Either; 2x + 3 = 0 or x - 2 = 0

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

304.

Find the value of x for which \(\frac{x - 5}{x(x - 1)}\) is defined

A.

0 or 5

B.

-5 or 5

C.

-11 or 5

D.

0 or 1

Correct answer is A

The expression \(\frac{x - 5}{x(x - 1)}\) is defined whten

x(x - 5) = 0.38

either x = 0 or x - 5 = 0

Hence, x = 0 or x = 5

305.

The total surface area of a hemispher is 75\(\pi cm^2\). Find the radius.

A.

5.0 cm

B.

7.0 cm

C.

8.5 cm

D.

12.0 cm

Correct answer is A

Total surface area of hemisphere is

3\(\pi r^2\) = 75\(\pi cm^2\)

\(r^2\) = \(\frac{75 \pi}{3 \pi}\)

\(r^2\) = 25

r = \(\sqrt{25}\)

r = 5cm