WAEC Mathematics Past Questions & Answers - Page 224

1,116.

Make t the subject of formula \(k = m\sqrt{\frac{t-p}{r}}\)

A.

\(\frac{rk^2 + p}{m^2}\)

B.

\(\frac{rk^2+pm^2}{m^2}\)

C.

\(\frac{rk^2-p}{m^2}\)

D.

\(\frac{rk^2-p^2}{m^2}\)

Correct answer is B

\(k = m\sqrt{\frac{t - p}{r}}\)

\(\frac{k}{m} = \sqrt{\frac{t - p}{r}}\)

\((\frac{k}{m})^2 = \frac{t - p}{r}\)

\(rk^2 = m^2 (t - p)\)

\(\therefore m^2 t = rk^2 + m^2 p\)

\(t = \frac{rk^2 + m^2 p}{m^2}\)

1,117.

Find the equation whose roots are -8 and 5

A.

\(x^2 + 13x + 40=0\)

B.

\(x^2 - 13x - 40=0\)

C.

\(x^2 - 3x +40=0\)

D.

\(x^2 + 3x - 40=0\)

Correct answer is D

Equation with roots -8 and 5: (x + 8)(x - 5) = 0

\(x^2 - 5x + 8x - 40 = 0\)

\(x^2 + 3x - 40 = 0\)

1,118.

Form an inequality for a distance d meters which is more than 18m, but not more than 23m

A.

18 ≤ d ≤ 23

B.

18 < d ≤ 23

C.

18 ≤ d < 23

D.

d < 18 or d > 23

Correct answer is B

No explanation has been provided for this answer.

1,119.

Simplify \(\frac{1}{x-3}-\frac{3(x-1)}{x^2 - 9}\)

A.

\(\frac{x-1}{x-3}\)

B.

\(\frac{-2}{x+3}\)

C.

\(\frac{x-1}{x+3}\)

D.

\(\frac{4x}{x^2-9}\)

Correct answer is B

\(\frac{1}{x-3}-\frac{3(x-1)}{x^2 - 9}\\
\frac{1}{x-3}-\frac{3(x-1)}{(x-3)(x+3)}\\
\frac{x+3-3x+3}{(x-3)(x+3)};\frac{-2x+6}{(x-3)(x+3)}\\
\frac{-2(x-3)}{(x-3)(x+3)}=\frac{-2}{x+3}\)

1,120.

Given that (2x + 7) is a factor of \(2x^2 + 3x - 14\), find the other factor

A.

x + 2

B.

2 - x

C.

x - 2

D.

x + 1

Correct answer is C

\(2x^2 + 3x - 14\)

\(2x^2 + 7x - 4x - 14\)

\(x(2x + 7) - 2(2x + 7)\)

= \((x - 2)(2x + 7)\)

The other factor = (x - 2).