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JAMB Mathematics 2018 Paper

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Question : 58

Total: 62

Simplify 25

\frac{1}{2}

\frac{-2}{3}

1 $\frac{1}{4}$
2 $\frac{1}{4}$
6
10

Solution:

Concept:

Use the laws of indices with fractional and negative powers.

Explanation:

25^{\frac{1}{2}}

means the square root of

25

.

So,

25^{\frac{1}{2}} = \sqrt{25} = 5

.

8^{-\frac{2}{3}}

means the reciprocal of the cube root of

8

, squared.

First,

\sqrt[3]{8} = 2

.

Then,

8^{-\frac{2}{3}} = 2^{-2} = \frac{1}{2^2} = \frac{1}{4}

.

Multiply the results:

5 \times \frac{1}{4} = \frac{5}{4} = 1\frac{1}{4}

.

Answer:

A.

1\frac{1}{4}

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