Question

Simplify the expression: $\left(\sqrt{5}-\sqrt{2}\right)\left(\sqrt{5}+\sqrt{2}\right)$

Answer 1

$\because a^2-b^2=(a+b)(a-b)$

$\therefore (\sqrt{5}+\sqrt{2})(\sqrt{5}-\sqrt{2})=(\sqrt{5}{)}^2-(\sqrt{2}{)}^2=5-2=3$