Test Index

WAEC Mathematics 2019 Paper

Question : 2

Total: 50

\;\frac{1}{3}

Solution:

Concept:

A negative index means take the reciprocal, and a fractional index

\frac{1}{3}

means take the cube root.

Explanation:

Convert the decimal to a fraction:

0.064 = \frac{64}{1000}

Therefore,

\left(0.064\right)^{-\frac{1}{3}} = \left(\frac{64}{1000}\right)^{-\frac{1}{3}}

By the rule

a^{-n} = \frac{1}{a^n}

, this becomes

\left(\frac{1000}{64}\right)^{\frac{1}{3}}

Taking the cube root of the numerator and denominator gives

\frac{\sqrt[3]{1000}}{\sqrt[3]{64}} = \frac{10}{4}

Simplify the fraction:

\frac{10}{4} = \frac{5}{2}

Answer:

\frac{5}{2}

, which is option A.

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