Further Mathematics questions and answers

Further Mathematics Questions and Answers

Test your knowledge of advanced level mathematics with this aptitude test. This test comprises Further Maths questions and answers from past JAMB and WAEC examinations.

546.

A function is defined by \(h : x \to 2 - \frac{1}{2x - 3}, x \neq \frac{3}{2}\). Find \(h^-1\), the inverse of h.

A.

\(\frac{3x - 4}{2x - 7}, x \neq \frac{7}{2}\)

B.

\(\frac{3x - 7}{2x - 4}, x \neq 2\)

C.

\(\frac{2x - 7}{4x - 3}, x \neq \frac{3}{4}\)

D.

\(\frac{4x - 7}{2x - 4}, x \neq 2\)

Correct answer is B

\(h : x \to 2 - \frac{1}{2x - 3}\)

\(h(x) = \frac{2(2x - 3) - 1}{2x - 3} = \frac{4x - 7}{2x - 3}\)

Let x = h(y)

\(x = \frac{4y - 7}{2y - 3}\)

\(x(2y - 3) = 4y - 7  \implies 2xy - 4y = 3x - 7\)

\(y = \frac{3x - 7}{2x - 4}\)

\(h^{-1}(x) = \frac{3x - 7}{2x - 4}\)

547.

If \(T = \begin{pmatrix} -2 & -5 \\ 3 & 8 \end{pmatrix}\), find \(T^{-1}\), the inverse of T.

A.

\(\begin{pmatrix} -8 & -5 \\ 3 & 2 \end{pmatrix}\)

B.

\(\begin{pmatrix} -8 & -5 \\ 3 & -2 \end{pmatrix}\)

C.

\(\begin{pmatrix} -8 & -5 \\ -3 & 2 \end{pmatrix}\)

D.

\(\begin{pmatrix} -8 & -5 \\ -3 & -2 \end{pmatrix}\)

Correct answer is A

Let \(\begin{pmatrix} a & b \\ c & d \end{pmatrix} = T^{-1}\)

\(T . T^{-1} = I\)

\(\begin{pmatrix} -2 & -5 \\ 3 & 8 \end{pmatrix}\begin{pmatrix} a & b \\ c & d \end{pmatrix} = \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}\)

\(\implies -2a - 5c = 1\)

\(-2b - 5d = 0 \implies b = \frac{-5d}{2}\)

\(3a + 8c = 0 \implies a = \frac{-8c}{3}\)

\(3b + 8d = 1\)

\(-2(\frac{-8c}{3}) - 5c = \frac{16c}{3} - 5c = \frac{c}{3} = 1 \implies c = 3\)

\(3(\frac{-5d}{2}) + 8d = \frac{-15d}{2} + 8d = \frac{d}{2} = 1 \implies d = 2\)

\(b = \frac{-5 \times 2}{2} = -5\)

\(a = \frac{-8 \times 3}{3} = -8\)

\(\therefore  T^{-1} = \begin{pmatrix} -8 & -5 \\ 3 & 2 \end{pmatrix}\)

548.

Find the derivative of \(\sqrt[3]{(3x^{3} + 1}\) with respect to x.

A.

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

B.

\(\frac{3x^{2}}{\sqrt[3]{(3x^{3} + 1)^{2}}}\)

C.

\(\frac{3x}{\sqrt[3]{3x^{2} + 1}}\)

D.

\(\frac{3x^{2}}{3(3x^{2} + 1)^{2}}\)

Correct answer is B

\(y = \sqrt[3]{3x^{3} + 1}  = (3x^{3} + 1)^{\frac{1}{3}}\)

Let u = \(3x^{3} + 1\); y = \(u^{\frac{1}{3}}\)

\(\frac{\mathrm d y}{\mathrm d x} = (\frac{\mathrm d y}{\mathrm d u})(\frac{\mathrm d u}{\mathrm d x})\)

\(\frac{\mathrm d y}{\mathrm d u} = \frac{1}{3}u^{\frac{-2}{3}}\)

\(\frac{\mathrm d u}{\mathrm d x} = 9x^{2}\)

\(\frac{\mathrm d y}{\mathrm d x} = (\frac{1}{3}(3x^{3} + 1)^{\frac{-2}{3}})(9x^{2})\)

= \(\frac{3x^{2}}{\sqrt[3]{(3x^{3} + 1)^{2}}}\) 

549.

If \(\frac{x + P}{(x - 1)(x - 3)} = \frac{Q}{x - 1} + \frac{2}{x - 3}\), find the value of (P + Q)

A.

-2

B.

-1

C.

0

D.

1

Correct answer is C

\(\frac{x + P}{(x-1)(x-3)} = \frac{Q}{x-1} + \frac{2}{x-3}\)

\(\frac{x + P}{(x-1)(x-3)} = \frac{Q(x-3) + 2(x-1)}{(x-1)(x-3)}\)

Comparing LHS and RHS of the equation, we have

\(x + P = Qx - 3Q + 2x -2\)

\(P = -3Q - 2\)

\(Q + 2 = 1 \implies Q = 1 - 2 = -1\)

\(P = -3(-1) - 2 = 3 - 2 = 1\)

\(P + Q = 1 + (-1) = 0\)

550.

A box contains 5 red and k blue balls. A ball is selected at random from the box. If the probability of selecting a blue ball is \(\frac{2}{3}\), find the value of k

A.

5

B.

6

C.

8

D.

10

Correct answer is D

\(p(blue) = \frac{\text{no of blue balls}}{\text{total no of balls}}\)

= \(\frac{2}{3} = \frac{k}{k + 5}\)

\(3k = 2(k + 5)  \implies 3k = 2k + 10\)

\(3k - 2k = k = 10\)