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.

2,456.
2,457.

If x = \(\begin{pmatrix} 1 & 2 \\ 0 & 3 \end{pmatrix}\) and y = \(\begin{pmatrix} 2 & 1 \\ 4 & 3 \end{pmatrix}\). Find xy.

A.

\(\begin{pmatrix} 10 & 7 \\ 12 & 9 \end{pmatrix}\)

B.

\(\begin{pmatrix} 2 & 7 \\ 4 & 17 \end{pmatrix}\)

C.

\(\begin{pmatrix} 10 & 4 \\ 4 & 6 \end{pmatrix}\)

D.

\(\begin{pmatrix} 4 & 3 \\ 10 & 9 \end{pmatrix}\)

Correct answer is A

\(\begin{pmatrix} 1 & 2 \\ 0 & 3 \end{pmatrix}\); y = \(\begin{pmatrix} 2 & 1 \\ 4 & 3 \end{pmatrix}\).

= \(\begin{pmatrix} 2 + 8 & 1 + 6 \\ 0 + 12 & 0 + 9 \end{pmatrix}\)

= \(\begin{pmatrix} 10 & 7 \\ 12 & 9 \end{pmatrix}\)

2,458.

\(\begin{vmatrix} -2 & 1 & 1 \\ 2 & 1 & k \\1 & 3 & -1 \end{vmatrix}\) = 23

A.

1

B.

2

C.

3

D.

4

Correct answer is B

-2(-1 - 3k) - 1(-2 -k) + 1(6 - 1) = 23

7k = 14

k = 2

2,459.

Find the sum to infinity of the following sequence \(1, \frac{9}{10}, (\frac{9}{10})^{2}, (\frac{9}{10})^{3}\)

A.

\(\frac{1}{10}\)

B.

\(\frac{9}{10}\)

C.

\(\frac{10}{9}\)

D.

10

Correct answer is D

\(S_{\infty} = \frac{a}{1 - r}\) (Sum to infinity of a G.P)

\(a = 1; r = \frac{9}{10}\)

\(S_{\infty} = \frac{1}{1 - \frac{9}{10}}\)

= \(\frac{1}{\frac{1}{10}} = 10\)

2,460.

If a \(\ast\) b = + \(\sqrt{ab}\), evaluate 2 \(\ast\)(12 \(\ast\) 27)

A.

12

B.

9

C.

6

D.

2

Correct answer is C

\(2 \ast (12 \ast 27)\)

\(12 \ast 27 = + \sqrt{12 \times 27}\)

= \(+ \sqrt{324} = 18\)

\(2 \ast 18 = + \sqrt{2 \times 18}\)

= \(+ \sqrt{36} = 6\)