WAEC Mathematics Past Questions & Answers - Page 35

171.

Solve \(\frac{1}{3}\)(5 - 3x) < \(\frac{2}{5}\)(3 - 7x)

A.

x > \(\frac{7}{22}\)

B.

x < \(\frac{7}{22}\)

C.

x > \(\frac{-7}{27}\)

D.

x < \(\frac{-7}{27}\)

Correct answer is D

\(\frac{1}{3}\)(5 - 3x) < \(\frac{2}{5}\)(3 - 7x)

5(5 - 3x) < 6(3 - 7x)

25 - 15x < 18 - 42x 

- 15x + 42x < 18 - 25

\(\frac{27x}{27}\) < \(\frac{-7}{27}\)

x < \(\frac{-7}{27}\)

172.

The first term of a geometric progression (G.P) is 3 and the 5th term is 48. Find the common ratio. 

A.

2

B.

4

C.

8

D.

16

Correct answer is A

T\(_5\) = ar\(^4\) 

\(\frac{48}{3} = \frac{3r^4}{3}\)

16 = r\(^4\) 

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

= 2

173.

~ y \(\to\) ~ x

A.

~ y \(\to\) ~ x

B.

y \(\to\) ~ x

C.

~ x \(\to\) ~ y

D.

y \(\to\) x

Correct answer is C

No explanation has been provided for this answer.

174.

Solve 3x - 2y = 10 and x + 3y = 7 simultaneously

A.

x = -4 and y = 1

B.

x = -1 and y = -4

C.

x = 1 and y = 4

D.

x = 4 and y = 1

Correct answer is D

3x - 2y = 10 - - x 3

x + 3y = 7 ---x 2

------------------------

9x - 6y = 30

2x + 6y = 14

-------------------------

\(\frac{11x}{11} \frac{44}{11}\) 

x = 4

From x + 3y = 7

3y = 7 - 4

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

y = 1

175.

If x = 3 and y = -1, evaluate 2(x\(^2\) - y\(^2\))

A.

24

B.

22

C.

20

D.

16

Correct answer is D

2(\(x^2 - y^2\))

= 2(x + y)(x - y)

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

= 2(2)(4) = 16