JAMB Mathematics Past Questions & Answers - Page 304

1,516.

Find the values of x and y respectively if
\(\begin{pmatrix} 1 & 0 \\ -1 & -1\\ 2 & 2 \end{pmatrix}\) + \(\begin{pmatrix} x & 1 \\ -1 & 0\\ y & -2 \end{pmatrix}\) = \(\begin{pmatrix} -2 & 1 \\ -2 & -1\\ -3 & 0 \end{pmatrix}\)

A.

-3, -2

B.

-5, -3

C.

-2, -5

D.

-3, -5

Correct answer is D

\(\begin{pmatrix} 1 & 0 \\ -1 & -1\\ 2 & 2 \end{pmatrix}\) + \(\begin{pmatrix} x & 1 \\ -1 & 0\\ y & -2 \end{pmatrix}\) = \(\begin{pmatrix} -2 & 1 \\ -2 & -1\\ -3 & 0 \end{pmatrix}\)

therefore, (x, y) = (-3, -5) respectively

1,517.

What value of x will make the function x(4 - x) a maximum?

A.

4

B.

3

C.

2

D.

1

Correct answer is C

x(4 - x)

4x - x2

\(\frac{dy}{dx}\) = 4 - 2x

\(\frac{dy}{dx}\) = 0

2x = 4

x = \(\frac{4}{2}\)

= 2

1,518.

Determine the value of x for which (x2 - 1)>0

A.

x < -1 or x > 1

B.

-1 < x < 1

C.

x > 0

D.

x < -1

Correct answer is A

x(x - 1) > 0 x < -1 or x > 1

1,519.

W is directly proportional to U. If W = 5 when U = 3, find U when W = \(\frac{2}{7}\)

A.

\(\frac{6}{35}\)

B.

\(\frac{10}{21}\)

C.

\(\frac{21}{10}\)

D.

\(\frac{35}{6}\)

Correct answer is A

W \(\alpha\) U

W = ku

u = \(\frac{w}{k}\); \(\frac{2}{7}\) x \(\frac{3}{5}\)

= \(\frac{6}{35}\)

1,520.

Find the standard deviation of 2, 3, 5 and 6

A.

√6

B.

√10

C.

√\(\frac{2}{5}\)

D.

√\(\frac{5}{2}\)

Correct answer is D

\(\begin{array}& x & x - \bar{x} & (x - \bar{x})^2 \\2 & -2 & 4 \\ 3 & -1 & 1 \\ 5 & 1 & 1 \\ 6 & 2 & 4\\ \hline \sum x = 16 & & \sum (x - \bar{x}^2) = 10 \end{array}\)
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\(\bar{x}\) = \(\frac{\sum x }{N}\)

= \(\frac{16}{4}\)

= 4

S = \(\sqrt{\frac {(x - \bar{x})^2}{N}}\)

= \(\sqrt{\frac {(10)}{4}}\)

= \(\sqrt{\frac {(5)}{2}}\)