WAEC Past Questions and Answers - Page 3923

19,611.

Find the value of x such that the expression \(\frac{1}{x}+\frac{4}{3x}-\frac{5}{6x}+1\) equals zero

A.

\(\frac{1}{6}\)

B.

\(\frac{1}{4}\)

C.

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

D.

\(\frac{-7}{6}\)

Correct answer is C

\(\frac{1}{x} + \frac{4}{3x} - \frac{5}{6x} + 1 = 0\)

\(\frac{6 + 8 - 5 + 6x}{6x} = 0\)

\(\frac{9 + 6x}{6x} = 0 \implies 9 + 6x = 0\)

\(6x = -9 \implies x = \frac{-3}{2}\)

19,612.

Solve the equation \(3y^2 = 27y\)

A.

y = o or 3

B.

y = 0 or 9

C.

y = -3 or 3

D.

y = 3 or 9

Correct answer is B

\(3y^2 = 27y\\
3y^2 - 27y = 0\\
3y(y - 9) = 0\\
3y = 0 or y - 9 = 0\\
y = 0 or y = 9\\
y = 0 or 9\)

19,613.

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

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

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

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

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

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

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

19,614.

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

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

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

19,615.

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.