WAEC Mathematics Past Questions & Answers - Page 93

461.

The coordinates of points P and Q are (4, 3) and (2, -1) respectively. Find the shortest distance between P and Q.

A.

10\(sqrt{2}\)

B.

4\(sqrt{5}\)

C.

5\(sqrt{2}\)

D.

2\(sqrt{5}\)

Correct answer is D

p(4, 3) Q(2 - 1)

distance = \(\sqrt{(x_2 - x_1)^2 + (Y_2 - y_1)^2}\)

= \(\sqrt{(2 - 4)^2 + (-1 - 3)^2}\)

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

= \(\sqrt{4 + 16}\)

= \(\sqrt{20}\)

= \(\sqrt{4 \times 5}\)

= 2\(\sqrt{5}\)

462.

Find the truth set of the equation x2 = 3(2x + 9)

A.

{x : x = 3, x = 9}

B.

{x : x = -3, x = -9}

C.

{x : x = 3, x = -9}

D.

{x : x = -3, x = 9}

Correct answer is D

x2 = 3(2x + 9)

x2 = 6x + 27

x2 - 6x - 27 = 0

x2 - 9x + 3x - 27 = 0

x(x - 9) + 3(x - 9) = (x + 3)(x - 9) = 0

x + 3 = 0 or x - 9 = 0

x = -3 or x = 9

x = -3, x = 9

463.

If x = {0, 2, 4, 6}, y = {1, 2, 3, 4} and z = {1, 3} are subsets of u = {x:0 \(\geq\) x \(\geq\) 6}, find x \(\cap\) (Y' \(\cup\) Z)

A.

{0, 2, 6}

B.

{1, 3}

C.

{0, 6)

D.

{9}

Correct answer is C

x = {0, 2, 4, 6}; y = {1, 2, 3, 4}; z = {1, 3}

u = {0, 1, 2, 3, 4, 5, 6}

y' = {0, 5, 6}

to find x \(\cap\) (Y' \(\cup\) Z)

first find y' \(\cup\) z = {0, 1, 3, 5, 6}

then x \(\cap\) (Y' \(\cup\) Z) = {0, 6}

464.

Three quarters of a number added to two and a half of the number gives 13. Find the number

A.

4

B.

5

C.

6

D.

7

Correct answer is A

let the number be x

2\(\frac{1}{2}x + \frac{3}{4}x = 13\)

\(\frac{5}{2}x + \frac{3}{4}x = 13\)

multiply through by 4

4(\(\frac{5}{2}\))x + 4(\(\frac{3}{4}\))x = 13 x 4

2(5x) + 3x = 52

10x + 3x = 52

13x = 52

x = \(\frac{52}{13}\)

x = 4

465.

Given that x > y and 3 < y, which of the following is/are true? i. y > 3 ii. x < 3 iii. x > y > 3

A.

i

B.

i and ii

C.

i and iii

D.

i, ii and iii

Correct answer is C

x > y and 3 < y; then 3 < y means that y > 3 x > 3 to give the possible x > y > 3