Question

The simplest rationalising factor of $2\sqrt{5}-\sqrt{3}$ is

• A. $2\sqrt{5}+3$
• B. $2\sqrt{5}+\sqrt{3}$
• C. $\sqrt{5}+\sqrt{3}$
• D. $\sqrt{5}-\sqrt{3}$

Answer 1

The correct option is B

$2\sqrt{5}+\sqrt{3}$

The simplest rationalising factor of $2\sqrt{5}-\sqrt{3}$ is $2\sqrt{5}+\sqrt{3}$ as $(\sqrt{a}+\sqrt{b})(\sqrt{a}-\sqrt{b})=a-b$.