WAEC Mathematics Past Questions & Answers - Page 295

1,471.

Solve the equation x\(^2\) - 2x - 3 = 0

A.

(-3, 1)

B.

(-1, -3)

C.

(3,1)

D.

(43, 0)

E.

(-1, 3).

Correct answer is E

x\(^2\) - 2x - 3 = 0

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

x(x - 3) + 1(x - 3) = 0

(x + 1)(x - 3) = 0

x = (-1, 3)

1,472.

Factorize the expression 2s\(^2\) - 3st - 2t\(^2\).

A.

(2s - t)(s + 2t)

B.

(2s + t)(s - 2t)

C.

(s + t)(2s - 1)

D.

(2s + t)(s -t)

E.

(2s + t)(s + 2t)

Correct answer is B

2s\(^2\) - 3st - 2t\(^2\)

= 2s\(^2\) - 4st + st - 2t\(^2\)

= 2s(s - 2t) + t(s - 2t)

= (2s + t)(s - 2t)

1,473.

Simplify: \(\frac{\log \sqrt{27}}{\log {81}}\)

A.

1/6

B.

3/8

C.

1/2

D.

3/4

E.

6

Correct answer is B

\(\frac{\log \sqrt{27}}{\log 81}\)

= \(\frac{\log \sqrt{3^3}}{\log 3^4}\)

= \(\frac{\log 3^{\frac{3}{2}}}{\log 3^4}\)

= \(\frac{\frac{3}{2} \log 3}{4 \log 3}\)

= \(\frac{\frac{3}{2}}{4}\)

= \(\frac{3}{8}\)

1,474.

Simplify: \(\frac{4^{-\frac{1}{2}} \times 16^{\frac{3}{4}}}{4^{\frac{1}{2}}}\)

A.

1/4

B.

0

C.

1

D.

2

E.

4

Correct answer is D

\(\frac{4^{-\frac{1}{2}} \times 16^{\frac{3}{4}}}{4^{\frac{1}{2}}}\)

= \(\frac{16^{\frac{3}{4}}}{4^{\frac{1}{2}} \times 4^{\frac{1}{2}}}\)

= \(\frac{(2^4)^{\frac{3}{4}}}{4^{\frac{1}{2}} \times 4^{\frac{1}{2}}}\)

= \(\frac{2^3}{4}\)

1,475.

The nth term of a sequence is given by (-1)\(^{n-2}\) x 2\(^{n-1}\). Find the sum of the second and third terms.

A.

-2

B.

1

C.

2

D.

6

E.

12

Correct answer is A

when n = 2

(-1)\(^{n-2}\) 2\(^{n+1}\) = 2

When n = 3

(-1)\(^{n-2}\) 2\(^{n+1}\) = -4

Sum = 2 - 4 = -2