Question

Find the rationalise factor of √7-√5

Answer 1

The rationalise factor of $\sqrt7-\sqrt5$ is $\sqrt 7+\sqrt5$ .

Lets rationalise $\sqrt7-\sqrt5$ :

$= (\sqrt7-\sqrt5)*\frac{\sqrt7+\sqrt5}{\sqrt7+\sqrt5}\\\\=\frac{(\sqrt7)^2-(\sqrt5)^2}{\sqrt7+\sqrt5} \\\\=\frac{7-5}{\sqrt7+\sqrt5} \\\\=\frac{2}{\sqrt7+\sqrt5}$