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WAEC Further Mathematics Past Questions & Answers - Page 105

521.

Evaluate \frac{\tan 120° + \tan 30°}{\tan 120° - \tan 60°}

A.

\sqrt{3} + \sqrt{2}

B.

\frac{2}{3}

C.

\frac{1}{3}

D.

-2\sqrt{3}

Correct answer is C

No explanation has been provided for this answer.

522.

Find \lim\limits_{x \to 3} (\frac{x^{3} + x^{2} - 12x}{x^{2} - 9})

A.

\frac{7}{2}

B.

0

C.

\frac{-7}{2}

D.

-7

Correct answer is A

\lim\limits_{x \to 3} (\frac{x^{3} + x^{2} - 12x}{x^{2} - 9}) = \lim\limits_{x \to 3} (\frac{x^{3} - 3x^{2} + 4x^{2} - 12x}{(x - 3)(x + 3)}

\lim\limits_{x \to 3} (\frac{(x^{2} + 4x)(x - 3)}{(x - 3)(x + 3)} = \lim\limits_{x \to 3} (\frac{x^{2} + 4x}{x + 3})

=\frac{3^{2} + 4(3)}{3 + 3} = \frac{21}{6} = \frac{7}{2}

523.

Find the distance between the points (2, 5) and (5, 9).

A.

4 units

B.

5 units

C.

12 units

D.

14 units

Correct answer is B

Distance between two points (a, b) and (c, d) = \(\sqrt{(d - b)^{2} + (c - a)^{2}}

Distance between (2, 5) and (5, 9) = \sqrt{(9-5)^{2} + (5-2)^{2}}

= \sqrt{16 + 9} = \sqrt{25} = 5 units

524.

A ball is thrown vertically upwards with a velocity of 15ms^{-1}. Calculate the maximum height reached. [g = 10ms^{-2}]

A.

15.25m

B.

13.25m

C.

11.25m

D.

10.25m

Correct answer is C

Maximum height (H) = \frac{u^{2}}{2g}

= \frac{15^{2}}{2 \times 10} = \frac{225}{20}

= 11.25m

525.

If the points (-1, t -1), (t, t - 3) and (t - 6, 3) lie on the same straight line, find the values of t.

A.

t = -2 and 3

B.

t = 2 and -3

C.

t = 2 and 3

D.

t = -2 and -3

Correct answer is C

For collinear points (points on the same line), the slopes are equal for any 2 points on the line.

Given (-1, t - 1), (t, t - 3), (t - 6, 3), 

slope = \frac{(t-3) - (t-1)}{t - (-1)} = \frac{3 - (t-3)}{(t-6) - t} = \frac{3 - (t-1)}{(t-6) - (-1)}

Taking any two of the equations above, solve for t.

\frac{t - 3 - t + 1}{t + 1} = \frac{6 -t}{-6}

12 = (6 - t)(t + 1)

-t^{2} + 5t + 6 - 12 = 0 \implies t^{2} - 5t + 6 = 0

Solving, we have t = 2 and 3.