Mathematics questions and answers

Mathematics Questions and Answers

How good are you with figures and formulas? Find out with these Mathematics past questions and answers. This Test is useful for both job aptitude test candidates and students preparing for JAMB, WAEC, NECO or Post UTME.

3,991.

A man 1.7m tall observes a bird on top of a tree at an angle of 30°. if the distance between the man's head and the bird is 25m, what is the height of the tree?

A.

26.7m

B.

14.2m

C.

\(1.7+(25\frac{\sqrt{3}}{3}m\)

D.

\(1.7+(25\frac{\sqrt{2}}{2}m\)

Correct answer is B

Hint: Make a sketch forming a right angled triangle. Let x = height of the tree above the man. Such that x/25 = sin 30.

x = 12.5m

The height of the tree = 12.5 + 1.7

= 14.2 m

3,992.

Find a positive value of \(\alpha\) if the coordinate of the centre of a circle x\(^2\) + y\(^2\) - 2\(\alpha\)x + 4y - \(\alpha\) = 0 is (\(\alpha\), -2) and the radius is 4 units.

A.

1

B.

2

C.

3

D.

4

Correct answer is C

\(x^{2} + y^{2} - 2\alpha x + 4y - \alpha = 0\)

r = 4 units; centre (\(\alpha\), -2).

\((x - x_{1})^{2} + (y - y_{1})^{2} = r^{2}\)

\((x - \alpha)^{2} + (y - (-2))^{2} = 4^{2}\)

\(x^{2} - 2\alpha x + \alpha^{2} + y^{2} + 4y + 4 = 16\)

\(\alpha(\alpha - 3) + 4(\alpha - 3) = 0\)

\((\alpha + 4)(\alpha - 3) = 0 \implies +\alpha = 3\)

\(x^{2} + y^{2} - 2\alpha x + 4y = 16 - \alpha^{2} - 4\)

\(\therefore 12 - \alpha^{2} = \alpha \implies \alpha^{2} + \alpha - 12 = 0\)

\(\alpha^{2} - 3\alpha + 4\alpha - 12 = 0\)

3,993.

Divide 4x\(^3\) - 3x + 1 by 2x - 1

A.

2x2-x+1

B.

2x2-x-1

C.

2x2+x+1

D.

2x2+x-1

Correct answer is D

No explanation has been provided for this answer.

3,994.

The first term of a geometric progression is twice its common ratio. Find the sum of the first two terms of the G.P if its sum to infinity is 8.

A.

8/5

B.

8/3

C.

72/25

D.

56/9

Correct answer is C

Let the common ratio be r so that the first term is 2r.

Sum, s = \(\frac{a}{1-r}\)

ie. 8 = \(\frac{2r}{1-r}\)

8(1-r) = 2r,

8 - 8r = 2r

8 = 2r + 8r

8 = 10r

r = \(\frac{4}{5}\).

where common ratio (r) = \(\frac{second term(n_2)}{first term(a)}\),

r = \(\frac{n_2}{2r}\)

r = \(\frac{4}{5}\) and a = 2r or \(\frac{8}{5}\)

\(\frac{4}{5}\) * \(\frac{8}{5}\) = n\(_2\)

\(\frac{32}{25}\) = n\(_2\)

The sum of the first two terms = a + n\(_2\)

= \(\frac{8}{5}\) + \(\frac{32}{25}\)

= \(\frac{40 + 32}{25}\)

= \(\frac{72}{25}\)

3,995.

Express \(\frac{1}{x^{3}-1}\) in partial fractions

A.

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

B.

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

C.

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

D.

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

Correct answer is A

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

\(x^{3} - 1 = (x - 1)(x^{2} + x + 1)\)

\(\frac{1}{x^{3} - 1} = \frac{A}{x - 1} + \frac{Bx + C}{x^{2} + x + 1}\)

\(\frac{1}{x^{3} - 1} = \frac{A(x^{2} + x + 1) + (Bx + C)(x - 1)}{x^{3} - 1}\)

Comparing the two sides of the equation,

\(A + B = 0 ... (1)\)

\(A - B + C = 0 ... (2)\)

\(A - C = 1 ... (3)\)

From (3), \(C = A - 1\), putting that in (2),

\(A - B = -C \implies A - B = 1 - A\)

\(2A - B = 1 ... (4)\)

(1) + (4): \(3A = 1 \implies A = \frac{1}{3}\)

\(A = -B \implies B = -\frac{1}{3}\)\(C = A - 1 \implies C = \frac{1}{3} - 1 = -\frac{2}{3}\)

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