Question

Rationalise the denominator of $\frac{4}{\sqrt{7}+\sqrt{5}}$

Answer 1

$\frac{4}{\sqrt{7}+\sqrt{5}}\times \frac{\sqrt{7}-\sqrt{5}}{\sqrt{7}-\sqrt{5}}\Rightarrow \frac{4(\sqrt{7}-\sqrt{5})}{2}\Rightarrow 2(\sqrt{7}-\sqrt{5})$