JAMB Mathematics Past Questions & Answers - Page 344

1,716.

Evaluate Log28 + Log216 - Log24

A.

3

B.

4

C.

5

D.

6

Correct answer is C

\( = log_2 \frac{8 \times 16}{4}\)

\( = log_2 32\)

\( = log_2 2^5\)

\( = 5log_2 2\)

\( = 5 \times 1\)

\( = 5 \)

1,717.

Simplify \(\frac{2\sqrt{2} - \sqrt{3}}{\sqrt{2} + \sqrt{3}}\)

A.

3\(\sqrt{6} - 7\)

B.

3\(\sqrt{6} + 7\)

C.

3\(\sqrt{6} - 1\)

D.

3\(\sqrt{6} + 1\)

Correct answer is A

\(= \frac{2\sqrt{2} - \sqrt{3}}{\sqrt{2} + \sqrt{3}} \times \frac{\sqrt{2} - \sqrt{3}}{\sqrt{2} - \sqrt{3}}\)

\(= \frac{2\sqrt{2}(\sqrt{2}) + (2\sqrt{2})(-\sqrt{3})-\sqrt{3}(\sqrt{2})-\sqrt{3}(-\sqrt{3})}{(\sqrt{2})^2-(\sqrt{3})^2}\)

\(= \frac{2 \times 2 - 2\sqrt{6} - \sqrt{6} + 3}{2 - 3}\)

\(= \frac{4 - 3\sqrt{6} + 3}{-1}\)

\(= \frac{7 - 3\sqrt{6}}{-1}\)

\(= \frac{7}{-1} - \frac{3\sqrt{6}}{-1}\)

\(= -7 + 3\sqrt{6}\)

\(= 3\sqrt{6}-7\)

1,718.

Solve for x in 8x-2 = 2/25

A.

4

B.

5

C.

8

D.

10

Correct answer is D

8x-2 = 2/25

x-2 = 2/25 x 1/8

x-2 = 2/200

x-2 = 1/100

1/x2 = 1/100

x2 = 100

x = 10

1,719.

If log7.5 = 0.8751, evaluate 2 log75 + log750

A.

6.6252

B.

6.6253

C.

66.252

D.

66.253

Correct answer is B

If log 7.5 = 0.8751
Then 2log75 + log750
= 2(1.8751) + 2.8751
= 3.7502 + 2.8751
= 6.6253

1,720.

A man donates 10% of his monthly net earnings to his church. If it amounts to N4,500, what is his net monthly income?

A.

N40,500

B.

N45,000

C.

N52,500

D.

N62,000

Correct answer is B

Let;
M = Man monthly net earnings

Then;

\(\text{N4500} = \frac{\text{10%}}{\text{100%}} \times M \)

\(M = \frac{\text{N4500} \times \text{100%}}{\text{10%}} \)

M = N45,000