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Simplifying expressions using the laws of indicesFractions as indices - Rule 2

Indices show where a number has been multiplied by itself, eg squared or cubed, or to show roots of numbers, eg square root. Some terms with indices can be simplified using the laws of indices.

Part of MathsNumerical skills

Fractions as indices - Rule 2

This rule is extended to:

\({a^{\frac{m}{n}} = \sqrt[n]{a}^m}\)

Examples

Simplify \(16^{\frac{3}{2}}\)

Answer

\(=(\sqrt{16})^{3}\)

\(=4^{3}\)

\(=64\)

Simplify \(32^{\frac{3}{5}}\)

Answer

=\((\sqrt[5]{32})^{3}\)

\(= 2^{3}\)

\(=8\)

Simplify \(8^{\frac{-2}{3}}\)

Answer

\(=(\sqrt[3]{8})^{-2}\)

\(=2^{-2}\)

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

\(=\frac{1}{4}\)

Simplify \(y^{\frac{-3}{4}}\times y^{\frac{1}{4}}\)

Answer

Add the indices \(\frac{-3}{4}+\frac{1}{4}=\frac{-2}{4}\) which simplifies to \(\frac{-1}{2}\)

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

Now try the example questions below.

Question

Simplify \(49^{\frac{3}{2}}\)

Question

Simplify \(27^{\frac{-2}{3}}\)

Question

Simplify \(y^{\frac{-2}{3}}\times y^{\frac{7}{3}}\)