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WAEC Mathematics Past Questions & Answers - Page 61

301.

Find  the nth term of the sequence 2 x 3, 4 x 6, 8 x 9, 16 x 12...

A.

2n x 3(n + 1)

B.

2n x 3n

C.

2n x 3n

D.

2n x 3n1

Correct answer is B

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

21 x 3 x 1, 22 x 3 x 2, 23 x 3 x 3, 24 x 3 x 4,.... 2n 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

= (x2+4x+4)(4x2+4x+1)

= x2 + 4x + 4 - 4 x2 - 4x - 1

= -3 x2 + 3

= 3 - 3 x2

= 3(1 - x2)

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

303.

Solved the equation 2x2x6 = 0

A.

x = 32 or 2

B.

x = -2 or 32

C.

x = -3 or 2

D.

x = 3 or -2

Correct answer is A

2x2x6 = 0

2x24x+3x6 = 0

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

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

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

x = 32 or x = 2

304.

Find the value of x for which x5x(x1) is defined

A.

0 or 5

B.

-5 or 5

C.

-11 or 5

D.

0 or 1

Correct answer is A

The expression x5x(x1) 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 75πcm2. 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

3πr2 = 75πcm2

r2 = 75π3π

r2 = 25

r = 25

r = 5cm