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 ofMathsNumber

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

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

\({a}^{n} ÷ {a}^{m} = {a}^{n-m}\)

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

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

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

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