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WAEC Mathematics Past Questions & Answers - Page 216

1,076.

if 4m+3n4m3n=52, find the ratio m:n

A.

7:4

B.

4:3

C.

3:4

D.

4:7

Correct answer is A

4m+3n4m3n=52

5(4m3n)=2(4m+3n)

20m15n=8m+6n

20m8m=6n+15n

12m=21n

2112=mn

m:n=7:4

1,077.

If y32<2y13, which of the following is true?

A.

y > 7

B.

y < -7

C.

y > -7

D.

y < 7

Correct answer is C

y32<2y13

3(y3)<2(2y1)

3y9<4y2

3y4y<2+9

y<7

y>7

1,078.

Simplify 2x13x+32

A.

x+36

B.

x+86

C.

x116

D.

x46

Correct answer is C

2x13x+32

= 2(2x1)3(x+3)6

= 4x23x96

= x116

1,079.

Factorize 6x2+7x20

A.

(6x - 5)(x + 4)

B.

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

C.

(3x+4)(2x-5)

D.

(3x-4)(2x+5)

Correct answer is D

6x2+7x20

= 6x2+15x8x20

= 3x(2x+5)4(2x+5)

= (3x4)(2x+5)

1,080.

Evaluate x2+x22x2+x3 when x = -1

A.

-2

B.

-1

C.

12

D.

1

Correct answer is D

x2+x22x2+x3

= x2+2xx22x2+3x2x3

= x(x+2)1(x+2)x(2x+3)1(2x+3)

= (x1)(x+2)(x1)(2x+3)

= x+22x+3

At x = -1, 

= 1+22(1)+3

= 11

= 1