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.

2,221.

Simplify \(\frac{324 - 4x^2}{2x + 18}\)

A.

2(x - 9)

B.

2(9 + x)

C.

81 - x2

D.

-2(x - 9)

Correct answer is D

\(\frac{324 - 4x^2}{2x + 18}\) = \(\frac{18^2 - (2x)^2}{2x + 18}\)

= \(\frac{(18 - 2x)(18 + 2x)}{(2x + 18)}\)

18 - 2x = 2(9 - x)

or -2(x - 9)

2,222.

Solve for a positive number x such that \(2^{(x^3 - x^2 - 2x)} = 1\)

A.

4

B.

3

C.

2

D.

1

Correct answer is C

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

\(x^3 - x^2 - 2x = 0\)

\(x(x^2 - x - 2) = 0\)

\(x^2 - x - 2 = 0\)

\((x + 1)(x - 2) = 0\)

x = 2 is the positive answer.

2,223.

If \(f(x) = 2x^2 - 5x + 3\), find f(x + 1).

A.

2x2 - x

B.

2x2 - x + 10

C.

4x2 + 3x + 2

D.

4x2 + 3x + 12

Correct answer is A

\(f(x) = 2x^2 - 5x + 3\)

\(f(x + 1) = 2(x + 1)^2 - 5(x + 1) + 3\)

= \(2(x^2 + 2x + 1) - 5x - 5 + 3\)

= \(2x^2 + 4x + 2 - 5x - 2\)

= \(2x^2 - x\)

2,224.

The cost of dinner for a group of students is partly constant and partly varies directly as the number of students. If the cost is N74.00 when the number of is 20 and N96.00 when the number is 30, find the cost when there are 15 students

A.

N68.50

B.

N63.00

C.

N60.00

D.

N52.00

Correct answer is B

C = a + kS. If C = 74, S = 20

C = 96, S = 30, C= ? S = 15

74 = a + 20k......(1)

96 = a + 30k......(2)

subtract equation (1) from (2)

96 = a + 30k
-
74 = a + 20k
--------------
22 = 10k

k = 2.2

find a

74 = a + 44

a = 30

C = 30 + 2.2S

when S = 15, C = 30 + 2.2 x 15

= 30 + 33

= N63

2,225.

Make R the subject of the fomula S = \(\sqrt{\frac{2R + T}{2RT}}\)

A.

R = \(\frac{T}{(TS^2 + 1)}\)

B.

R = \(\frac{T}{2(TS^2 - 2)}\)

C.

R = \(\frac{T}{2(TS^2 + 1)}\)

D.

R = \(\frac{R}{2(TS^2 + 1)}\)

Correct answer is B

S = \(\sqrt{\frac{2R + T}{2RT}}\)

Squaring both sides, 

\(S^{2} = \frac{2R + T}{2RT}\)

\(S^{2} (2RT) = 2R + T\)

\(2S^{2} RT - 2R = T\)

\(R = \frac{T}{2TS^{2}  - 2}\)

= \(\frac{T}{2(TS^{2} - 1)}