WAEC Further Mathematics Past Questions & Answers - Page 115

571.

A particle starts from rest and moves in a straight line such that its acceleration after t seconds is given by \(a = (3t - 2) ms^{-2}\). Find the other time when the velocity would be zero.

A.

\(\frac{1}{3} seconds\)

B.

\(\frac{3}{4} seconds\)

C.

\(\frac{4}{3} seconds\)

D.

\(2 seconds\)

Correct answer is C

Given \(a(t) = 3t - 2\), \(v(t) = \int (a(t)) \mathrm {d} t\)

= \(\int (3t - 2) \mathrm {d} t = \frac{3}{2}t^{2} - 2t\)

\(\frac{3}{2}t^{2} - 2t = 0 \implies t(\frac{3}{2}t - 2) = 0\)

\(t = \text{0 or t} = \frac{3}{2}t - 2 = 0 \implies t = \frac{4}{3}\)

The time t = 0 was the starting point, The next time v = 0 m/s is at \(t = \frac{4}{3} seconds\).

572.

Find the coordinates of the point which divides the line joining P(-2, 3) and Q(4, 6) internally in the ratio 2 : 3.

A.

\((5\frac{2}{5}, \frac{2}{5})\)

B.

\((\frac{2}{5}, 5\frac{2}{5})\)

C.

\((\frac{-2}{5}, 5\frac{2}{5})\)

D.

\((\frac{2}{5}, 4\frac{1}{5})\)

Correct answer is D

No explanation has been provided for this answer.

573.

Find \(\int \frac{x^{3} + 5x + 1}{x^{3}} \mathrm {d} x\)

A.

\(x^{2} + 10x + c\)

B.

\(x + \frac{5}{3}x^{3} + x^{4} + c\)

C.

\(x - 5x^{2} - 2x^{3} + c\)

D.

\(x - \frac{5}{x} - \frac{1}{2x^{2}} + c\)

Correct answer is D

\(\frac{x^{3} + 5x + 1}{x^{3}} \equiv  1 + \frac{5}{x^{2}} + \frac{1}{x^{3}}\)

\(\equiv \int (1 + \frac{5}{x^{2}} + \frac{1}{x^{3}}) \mathrm {d} x = \int (1 + 5x^{-2} + x^{-3}) \mathrm {d} x\)

= \((x - 5x^{-1} - \frac{1}{2}x^{-2} + c)\)

= \(x - \frac{5}{x} - \frac{1}{2x^{2}} + c\).

574.

If \(\begin{vmatrix}  1+2x & -1 \\ 6 & 3-x \end{vmatrix} = -3 \), find the values of x.

A.

\(x = 3, -2\)

B.

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

C.

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

D.

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

Correct answer is D

\(\begin{vmatrix} 1+2x & -1 \\ 6 & 3-x  \end{vmatrix} =  -3 \implies (1+2x)(3-x) - (-6) = -3\)

\(3 - x + 6x - 2x^{2} + 6 = -3\)

\(-2x^{2} + 5x + 3 + 6 + 3 = 0\)

Multiplying through with -1, 

\(2x^{2} - 5x -12 = 0\)

\((2x + 3)(x - 4) = 0 \implies x = \frac{-3}{2} , 4\)

575.

Each of the 90 students in a class speak at least Igbo or Hausa. If 56 students speak Igbo and 50 speak Hausa, find the probability that a student selected at random from the class speaks Igbo only.

A.

\(\frac{28}{45}\)

B.

\(\frac{4}{9}\)

C.

\(\frac{8}{45}\)

D.

\(\frac{1}{9}\)

Correct answer is B

Let the number of candidates that speak both Igbo and Hausa = x

The number that speaks Igbo only = 56 - x

The number that speaks Hausa only = 50 - x

56 - x + x + 50 - x = 90

106 - x = 90

x = 16

P(Igbo only) = \(\frac{56 - 16}{90} = \frac{4}{9}\)