WAEC Further Mathematics Past Questions & Answers - Page 73

361.

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

A.

0

B.

\(8\sqrt{3}\)

C.

13

D.

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

Correct answer is B

\((1 + 2\sqrt{3})^{2} = 1 + 4\sqrt{3} + 12 = 13 + 4\sqrt{3}\)

\((1 - 2\sqrt{3})^{2} = 1 - 4\sqrt{3} + 12 = 13 - 4\sqrt{3}\)

\(13 + 4\sqrt{3} - (13 - 4\sqrt{3}) = 13 + 4\sqrt{3} - 13 + 4\sqrt{3}\)

= \(8\sqrt{3}\) 

362.

Find the maximum value of \(2 + \sin (\theta + 25)\).

A.

1

B.

2

C.

3

D.

4

Correct answer is C

\(\sin \theta \leq 1\)

i.e Maximum value of \(\sin \theta \forall \theta = 1\).

Therefore, \(2 + \sin \theta \leq 2 + 1 = 3\)

363.

The initial velocity of an object is \(u = \begin{pmatrix} -5 \\ 3 \end{pmatrix} ms^{-1}\). If the acceleration of the object is \(a = \begin{pmatrix} 3 \\ -4 \end{pmatrix} ms^{-2}\) and it moved for 3 seconds, find the final velocity.

A.

\(\begin{pmatrix} -14 \\ 15 \end{pmatrix} ms^{-1}\)

B.

\(\begin{pmatrix} -2 \\ 1 \end{pmatrix} ms^{-1}\)

C.

\(\begin{pmatrix} 4 \\ -9 \end{pmatrix} ms^{-1}\)

D.

\(\begin{pmatrix} 14 \\ -9 \end{pmatrix} ms^{-1}\)

Correct answer is C

\(u = \begin{pmatrix} -5 \\ 3 \end{pmatrix} ms^{-1}\)

\(a = \begin{pmatrix} 3 \\ -4 \end{pmatrix} ms^{-2}; t = 3 secs\)

\(v = u + at \implies v = \begin{pmatrix} -5 \\ 3 \end{pmatrix} + \begin{pmatrix} 3 \\ -4 \end{pmatrix} \times 3\)

= \(\begin{pmatrix} -5 \\ 3 \end{pmatrix} + \begin{pmatrix} 9 \\ -12 \end{pmatrix} = \begin{pmatrix} 4 \\ -9 \end{pmatrix} ms^{-1}\)\)

364.