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WAEC Mathematics Past Questions & Answers - Page 35

171.

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

T5 = ar4 

483=3r43

16 = r4 

r = 416

= 2

172.

~ y ~ x

A.

~ y ~ x

B.

y ~ x

C.

~ x ~ y

D.

y x

Correct answer is C

No explanation has been provided for this answer.

173.

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

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

11x114411 

x = 4

From x + 3y = 7

3y = 7 - 4

3y3 = 33

y = 1

174.

If x = 3 and y = -1, evaluate 2(x2 - y2)

A.

24

B.

22

C.

20

D.

16

Correct answer is D

2(x2y2)

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

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

= 2(2)(4) = 16

175.

Given that 3+55 

= x + y15, find the value of (x + y) 

A.

135

B.

125

C.

115

D.

15

Correct answer is C

3+55  = x + y15

cross multiply to have: 35 =  x5 + 5y3

Collect like roots :   x5 =  5 → x = 1

                                5y3 =  3 → y = 15

∴ ( x + y ) = 1 + 15

= 115