WAEC Mathematics Past Questions & Answers - Page 90

446.

If \(\frac{2}{x - 3} - \frac{3}{x - 2}\) is equal to \(\frac{p}{(x - 3)(x - 2)}\), find p

A.

-x - 5

B.

-(x + 3)

C.

5x - 13

D.

5 - x

Correct answer is D

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

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

= \(\frac{2x - 4 - 3x + 9}{(x - 3)(x - 2)}\) = \(\frac{p}{(x - 3)(x - 2)}\)

\(\frac{-x + 5}{(x - 3)(x - 2)} = \frac{p}{(x - 3)(x - 2)}\)

p(x - 3)(x - 2) = -x + 5(x - 3)(x - 2)

p = -x + 5 or p = 5 - x

447.

Simplify \(\frac{\sqrt{8^2 \times 4^{n + 1}}}{2^{2n} \times 16}\)

A.

16

B.

8

C.

4

D.

1

Correct answer is C

\(\frac{\sqrt{8^2 \times 4^{n + 1}}}{2^{2n} \times 16}\)

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

= \(\frac{\sqrt{2^6 \times 2^{2n + 2)}}}{2^{2n} + 4}\)

= \(\frac{\sqrt{2^6 + 2^{2n + 2)}}}{2^{2n} + 4}\)

= \(\frac{\sqrt{2^{2n + 8}}}{2^{2n} + 4}\)

= \(\sqrt{2^{2n + 8} \div 2^{2n} + 4}\)

= \(\sqrt{2^{2n - 2n} + 8 - 4}\)

= \(\sqrt{2^4}\)

= \(\sqrt{16}\)

= 4

448.

Approximate 0.0033780 to 3 significant figures

A.

338

B.

0.338

C.

0.00338

D.

0.003

Correct answer is C

No explanation has been provided for this answer.

449.

Given that cos x = \(\frac{12}{13}\), evaluate \(\frac{1 - \tan x}{\tan x}\)

A.

\(\frac{5}{13}\)

B.

\(\frac{5}{7}\)

C.

\(\frac{7}{5}\)

D.

\(\frac{13}{5}\)

Correct answer is C

cos x\(\frac{12}{13}\)

132 = 122 + a2

169 = 144 + a2

a2 = 169 - 144

a2 = 25

a \(\sqrt{25}\)

a = 5

tan x = \(\frac{5}{12}\)

\(\frac{1 - \tan x}{\tan x} = \frac{1 - \frac{5}{12}}{\frac{5}{12}}\)

\(\frac{\frac{1 - \frac{5}{12}}{12 - 5}}{12} = \frac{\frac{7}{12}}{\frac{5}{12}}\)

= \(\frac{7}{2} \div \frac{5}{12}\)

= \(\frac{7}{12} \times \frac{12}{5} = \frac{7}{5}\)

450.

If x : y = 3 : 2 and y : z = 5 : 4, find the value of x in the ratio x : y : z

A.

8

B.

10

C.

15

D.

20

Correct answer is C

No explanation has been provided for this answer.