JAMB Mathematics Past Questions & Answers

796.

Write the decimal number 39 to base 2

10011 base 2

110111 base 2

111001 base 2

100101 base 2

19.5 base 2

View answer & explanation

Correct answer is A

$\begin{array}{c|c} 2 & 39\\ 2 & 19 R 1\\ 2 & 9 R 1\\2 & 4 R 0\\2 & 1 R 0\\ 2 & 1 R 1\end{array}$

= 10011 base 2

797.

If x varies inversely as y, and y varies directly as the square root of z, and z varies directly $\frac{1}{w^2}$ write down in words how x varies with w

x varies inversely as w²

x varies directly as w²

x varies directly as w

x varies inversely as w

x varies directly as square root of w

View answer & explanation

Correct answer is B

No explanation has been provided for this answer.

798.

A cylindrical motor of height 12cm has uniform thickness of 2cm. If the diameter of its outer cross section is 10cm, Find the volume of the constituent material. (take $\pi$ = $\frac{22}{7}$

$\frac{6600}{7}$ cm³

270cm³

660cm³

$\frac{4224}{7}$ cm³

$\frac{1980}{7}$ cm³

View answer & explanation

Correct answer is D

V = $\pi$ r²h

= $\frac{22}{7}$ x 5² x 12 - $\frac{22}{7}$ x 3² x 12

= $\frac{22}{7}$ x 12(5² - 3²)

= $\frac{4224}{7}$

799.

If a function is defined by f(x + 1) = 3x2 - x + 4, Find f(0).

View answer & explanation

Correct answer is D

f(x + 1) = 3x2 - x + 4

f(0) = f(x + 1)

x + 1 = 0 ===> x = -1

f(0) = 3(-1)2 - (-1) + 4

f(0) = 3 + 1 + 4

= 8

800.

The expression x $^3$ - 4x $^2$ + cx + d is such that x + 1 is its factor, and its value is 1 when x is -2. Find c and d.

c = 4 and d = -9

c = -4 and d = 9

c = -20 and d = -15

c = 20 and d = -15

c = -20 and d = 15

View answer & explanation

Correct answer is C

F(X) = x $^3$ - 4x $^2$ + cx + d

= (X + 1) Q(X) + R

x = -1, R = 0,f(-1) = -1 $^3$ - 4(-1) $^2$ + c(-1) + d = 0

-1 - 4 - c + d = 0

d - c = 5................(i)

f(-2) = -2 $^3$ - 4(-2) $^2$ + c(-2) + d = 1

= -8 - 16 - 2c + d

= 1

-8 - 16 - 2c + d = 1

-24 - 2c + d = 1

d - 2c = 1 + 24

d - 2c = 25.................(ii)

$\frac{d - c = 5}{-c = 20}$ d - c = 5

c = -20

d - (-20) = 5

d + 20 = 5

d = 5 - 20

= -15

c = -20, d = -15