WAEC Further Mathematics Past Questions & Answers - Page 48

236.

Two functions f and g are defined by \(f : x \to 3x - 1\) and \(g : x \to 2x^{3}\), evaluate \(fg(-2)\)

A.

-49

B.

-47

C.

-10

D.

-9

Correct answer is A

\(g : x \to 2x^{3}\)

\(g(-2) = 2(-2^{3}) = 2(-8) = -16\)

\(f : x \to 3x - 1\)

\(f(-16) = 3(-16) -1 = -48 - 1 = - 49\)

237.

If \((x - 3)\) is a factor of \(2x^{3} + 3x^{2} - 17x - 30\), find the remaining factors.

A.

(2x - 5)(x - 2)

B.

(2x - 5)(x + 2)

C.

(2x + 5)(x - 2)

D.

(2x + 5)(x + 2)

Correct answer is D

Divide \(2x^{3} + 3x^{2} - 17x - 30\) by \((x - 3)\). You get \(2x^{2} + 9x + 10\).

Factorizing, we have \(2x^{2} + 9x + 10 = 2x^{2} + 4x + 5x + 10\)

\(2x(x + 2) + 5(x + 2)\)

= \((2x + 5)(x + 2)\)

238.

A binary operation ♦ is defined on the set R, of real numbers by \(a ♦ b = \frac{ab}{4}\). Find the value of \(\sqrt{2} ♦ \sqrt{6}\)

A.

\(\sqrt{3}\)

B.

\(\frac{3\sqrt{2}}{4}\)

C.

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

D.

\(\frac{\sqrt{2}}{2}\)

Correct answer is C

\(a ♦ b = \frac{ab}{4}\)

\(\sqrt{2} ♦ \sqrt{6} = \frac{\sqrt{2} \times \sqrt{6}}{4} = \frac{\sqrt{12}}{4}\)

= \(\frac{2\sqrt{3}}{4} \)

= \(\frac{\sqrt{3}}{2}\)

239.

Simplify \(\sqrt{(\frac{-1}{64})^{\frac{-2}{3}}}\)

A.

-4

B.

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

C.

\(\frac{1}{8}\)

D.

4

Correct answer is D

\((\frac{-1}{64})^{\frac{-2}{3}} = -64^{\frac{2}{3}}\)

\((-4^{3})^{\frac{2}{3}} = -4^{2} = 16\)

\(\therefore \sqrt{(\frac{-1}{64})^{\frac{-2}{3}} = \sqrt{16} = 4\)

240.

Solve the inequality \(2x^{2} + 5x - 3 \geq 0\).

A.

\(x \leq -3\) or \(x \geq \frac{1}{2}\)

B.

\(x < -\frac{1}{2}\) or \(x \geq 3\)

C.

\(-3 \leq x \leq \frac{1}{2}\)

D.

\(-\frac{1}{2} \leq x \leq 3\)

Correct answer is A

No explanation has been provided for this answer.