JAMB Mathematics Past Questions & Answers - Page 161

801.

Find the missing numerator \(\frac{5}{x + 1}\) - \(\frac{3}{1 - x}\) - \(\frac{7x - 1}{x^2 - 1}\) = \(\frac{?}{x + 1}\).

A.

-1

B.

x - 1

C.

\(\frac{3(1 - 5x)}{x + 1}\)

D.

1

E.

3(1 - 5x)

Correct answer is D

\(\frac{5}{x + 1} - \frac{3}{1 - x} - \frac{7x - 1}{x^{2} - 1} = \frac{?}{x + 1}\)

\(\frac{5(x - 1) - 3(- (x + 1)) - 7x - 1}{x^{2} - 1}\)

= \(\frac{5x - 5 + 3x + 3 - 7x - 1}{x^{2} - 1}\)

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

= \(\frac{x - 1}{(x - 1)(x + 1)}\)

= \(\frac{1}{x + 1}\).

The numerator = 1.

802.

Simplify 102 + log105

A.

500

B.

2 log10 5

C.

10

D.

25

E.

log105 x 10100

Correct answer is E

102 + log105 = log10 10100 + log105

= log105 x 10100

803.

Given log 2 = 0.69, log3 = 1, 10 and log7 = 1.90, all to a fixed base, find log 10.5 to the same base without using tables.

A.

1.03

B.

2.31

C.

3.69

D.

10.5

E.

25

Correct answer is B

log 10.5 = log \(\frac{21}{2}\)

= log 21 - log 2

= log(3 x 7) - log 2

= log 3 + log 7 - log 2

= 1.10 + 1.90 - 0.69

= 3 - 0.69

= 2.31

804.

Solve the equation for the positive values of \(\theta\) less than 360o. 3 tan \(\theta\) + 2 = -1

A.

135o or 315o

B.

45o or 135o

C.

315o or 180o

D.

315v + 45o

E.

360o or 315o

Correct answer is A

3 tan \(\theta\) + 2 = -1

3 tan \(\theta\) \(\frac{-3}{3}\) = -1

\(\theta\) = tan -1(-1)

\(\theta\) = 360o - 45o

= 315o

\(\theta\) = 180 - 45o = 135o

805.

Find the area of the curved surface of a cone whose base radius is 6cm and whose height is 8cm. (take \(\pi\) = \(\frac{22}{7}\))

A.

188.57cm2

B.

1320cm2

C.

188cm2

D.

188.08cm2

E.

10cm2

Correct answer is A

S = curved surface area = \(\pi\)rL

= \(\frac{22}{7}\) x 6 x 10

= 188.57cm2