Question

The simplest rationalising factor of $\sqrt{3}+\sqrt{5}$ is

• A. $\sqrt{3}-5$
• B. $3-\sqrt{5}$
• C. $\sqrt{3}-\sqrt{5}$
• D. $\sqrt{3}+\sqrt{5}$

Answer 1

The correct option is C

$\sqrt{3}-\sqrt{5}$

The simplest rationalising factor of $\sqrt{3}+\sqrt{5}$ is $\sqrt{3}-\sqrt{5}$ as $(\sqrt{a}+\sqrt{b})(\sqrt{a}-\sqrt{b})=a-b$.