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WAEC Mathematics Past Questions & Answers - Page 148

736.

Given that x = 2 and y = - $\frac{1}{4}$ , evaluate $\frac{x^2y - 2xy}{5}$

zero

$\frac{1}{5}$

Correct answer is A

Given; x = 2; y = $\frac{-1}{4}$

= $\frac{x^2y - 2xy}{5}$

= $\frac{2^2(\frac{-1}{4}) - 2(2)(\frac{-1}{4})}{5}$

= $\frac{4(\frac{-1}{4}) + 4(\frac{-1}{4})}{5}$

= $\frac{1 + 1}{5}$

= $\frac{0}{5}$

= 0

737.

Simplify 3 $\sqrt{27x^3y^9}$

9xy³

3xy⁶

3xy³

9y³

View answer & explanation

Correct answer is C

3 $\sqrt{27x^3y^9}$ = 3 $\sqrt{27} \times 3\sqrt{3^3} \times 3\sqrt{y^9}$

= 3 $\times x \times y^3$

= 3xy³

738.

Simplify $\frac{\frac{1}{x} + \frac{1}{y}}{x + y}$

$\frac{1}{x + y}$

$\frac{1}{xy}$

x + y

View answer & explanation

Correct answer is B

$\frac{\frac{1}{x} + \frac{1}{y}}{x + y}$ = $\frac{\frac{y + x}{xy}}{x + y}$

= $\frac{x + y}{xy}$

= $\frac{x + y}{xy} \times \frac{1}{x + y}$

= $\frac{1}{xy}$

739.

If p-2g + 1 = g + 3p and p - 2 = 0, find g

-2

-1

View answer & explanation

Correct answer is B

p - 2g + 1 = g + 3p.........(1)

p - 2 = 0 .........(2)

From (2), p = 2; put p = 2 into (1);

2 - 2g + 1 = g + 3(2)

3 - 2g = g + 6

-2g - g = 6 - 3

-3g = 3

g = $\frac{3}{-3}$

g = -1

740.

A trader bought 100 tubers at 5 for N350.00. She sold them in sets of 4 for N290.00. Find her gain percent.

3.6%

3.5%

3.4%

2.55

View answer & explanation

Correct answer is A

Cost price, c.p = $\frac{100}{5}$ x N350 = N7000

Selling price, s.p = $\frac{100}{5}$ x N290 = N7250

%Gain = $\frac{S.p - C.p}{C.p}$ x 100%

= $\frac{7250 - 7000}{7000}$ x 100% = $\frac{250 \times 100}{7000}$

= 3.6% (approx.)