WAEC Mathematics Past Questions & Answers - Page 248

1,236.

Find (X-Y) if 4x - 3y = 7 and 3x - 2y = 5

A.

4

B.

3

C.

2

D.

-2

E.

-3

Correct answer is C

No explanation has been provided for this answer.

1,237.

Find the equation whose roots are \(\frac{2}{3}and \frac{-1}{4}\)

A.

\(12x^2-5x+2=0\)

B.

\(12x^2-11x+2=0\)

C.

\(x^2-\frac{11}{12}x+2=0\)

D.

\(x^2+\frac{11}{12}x-2=0\)

E.

\(12x^2+11x+2=0\)

Correct answer is A

x\(^2\) - (sum of given roots)x + (product of given roots ) = 0
x\(^2\) - (\(\frac{2}{3} + \frac{-1}{4}\))x + (\(\frac{2}{3} * \frac{-1}{4}\)) = 0

x\(^2\) - (\(\frac{8 - 3}{12}\))x + (\(\frac{- 2}{12}\))

x\(^2\) - \(\frac{5}{12}\)x + \(\frac{- 2}{12}\)

multiply through by the LCM 12

12 * x\(^2\) - 12 * \(\frac{5}{12}\)x + 12 * \(\frac{- 2}{12}\)

12x\(^2\) - 5x - 2 = 0

1,238.

Make S the subject of the formula: \(V = \frac{K}{\sqrt{T-S}}\)

A.

\(T-\frac{K^2}{V^2} = S\)

B.

\(T+\frac{K^2}{V^2} = S\)

C.

\(T-\frac{K^2}{V} = S\)

D.

\(T-\frac{K}{V} = S\)

E.

\(T-\frac{K}{V^2} = S\)

Correct answer is A

\(V = \frac{K}{\sqrt{T-S}}\)
square both sides of the equation
\(V^2 = \frac{K^2}{T-S}\)
cross multiply
\(V^2 T - S = K^2\)
\(T - S = \frac{K^2}{V^2}\)
\(T = \frac{K^2}{V^2} + S\)
\(T - = \frac{K^2}{V^2} = S\)

1,239.

For what value of x is the expression

not defined?

A.

3, 1

B.

-1, -3

C.

-1, 3

D.

3, -2

E.

1, -3

Correct answer is C

x2 - 2x - 3 = 0
x2 - 3x + x - 3 = 0
x(x - 3) + (x - 3) = 0
(x + 1)(x - 3) = 0
x = -1 or 3

1,240.

p and q are two positive numbers such that p > 2q. Which one of the following statements is not true?

A.

-p < -2q

B.

-p > -2q

C.

-q < 2p

D.

q < 1/2p

E.

p2 > 2q2

Correct answer is B

No explanation has been provided for this answer.