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WAEC Further Mathematics Past Questions & Answers - Page 126

626.

Given n = 3, evaluate 1(n1)!1(n+1)!

A.

12

B.

212

C.

2

D.

1124

Correct answer is D

n = 3, 1(n1)!1(n+1)!=1(31)!1(3+1)!

= 12124=12124

= 1124

627.

Simplify nP5nC5

A.

80

B.

90

C.

110

D.

120

Correct answer is D

nP5nC5=n!(n5)!÷n!(n5)!5!

= n!(n5)!×(n5)!5!n!=5!=120

628.

If log10y+3log10xlog10x, express y in terms of x.

A.

y1x

B.

y1x

C.

y1x2

D.

y1x2

Correct answer is D

log10y+3log10xlog10x

log10ylog10x3log10x

log10y2log10x=log10ylog10x2

log10ylog10(1x2)y1x2

629.

Solve for x in the equation 5x×5x+1=25

A.

2

B.

12

C.

12

D.

2

Correct answer is C

5x×5x+1=25

5x×5x+1=52

5x+x+1=52, equating powers,

2x+1=22x=1

630.

If (2t - 3s)(t - s) = 0, find \frac{t}{s}

A.

\frac{3}{2} or 1

B.

\frac{3}{2} or -1

C.

\frac{-3}{2} or -1

D.

\frac{-3}{2} or 1

Correct answer is A

(2t - 3s)(t - s) = 0 \implies (2t - 3s) = \text{0 or} (t - s) = 0

2t - 3s = 0 \implies 2t = 3s \therefore \frac{t}{s} = \frac{3}{2}

t - s = 0 \implies t = s  \therefore  \frac{t}{s} = 1

\frac{t}{s} = \frac{3}{2} or 1