Please do as Subhotosh Khan has asked.
While thinking about the problem, it may help to remember these four fundamental rules about roots:
[MATH]\text {Given positive real numbers } a,\ b,\ c \text { and } d \text { and integer } n \ge 2:[/MATH]
[MATH]\sqrt{a} \equiv \sqrt[2]{a};[/MATH]
[MATH]b = \sqrt[n]{a} \iff b^ n = a;[/MATH]
[MATH]\sqrt[n]{c * d} \equiv \sqrt[n]{c} * \sqrt[n]{d} \text { and }[/MATH]
[MATH]\sqrt[n]{\dfrac{c}{d}} \equiv \dfrac{\sqrt[n]{c}}{\sqrt[n]{d}}.[/MATH]
So for example
[MATH]4^2 = 16 \implies 4 = \sqrt[2]{16} = \sqrt{16}.[/MATH]