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Index notation – WJECFractional indices

Indices are a way of representing numbers and letters that have been multiplied by themselves a number of times. They help us to complete problems involving powers more easily.

Part of MathsNumber

Fractional indices

The denominator is the root.

The numerator is the power.

Example one

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

Therefore, \({a}^\frac{1}{2} = (\sqrt{a})^{1}\)

Example two

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

= 22

= 4

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

Question

Evaluate \({16}^\frac{1}{2}\)

Question

Evaluate \({27}^\frac{2}{3}\)

Useful equations to know

\({a}^{n} \times {a}^{m} = {a}^{n+m}\)

\({a}^{n} ÷ {a}^{m} = {a}^{n-m}\)

\(({a}^{n})^{m} = {a}^{n \times m}\)

\({a}^{0} = {1}\)

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

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