WAEC Past Questions and Answers - Page 4084

20,416.

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)

20,417.

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)

20,418.

Which of the following parts of the tongue does not correspond to the taste indicated beside it?

A.

Tip/sweet

B.

Centre/salty

C.

Back/sour

D.

Side/sour

E.

Back/bitter

Correct answer is C

No explanation has been provided for this answer.

20,419.

Thunder is usually heard some seconds after lightning is observed because

A.

the human eye is more sensitive to light than the ear to sound

B.

sound and light travel in different media

C.

thunder occurs after lightning

D.

light travels faster than sound

Correct answer is D

No explanation has been provided for this answer.

20,420.

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

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

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

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

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

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

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