Question

State whether True or False

The square of $\sqrt{5}-2$ is $9-4\sqrt{5}$

Answer 1

By using formula $(a-b{)}^2=a^2-2ab+b^2$, we get
$\therefore {(\sqrt{5}-2)}^2=\left({\sqrt{5}}^2\right)-2\left(\sqrt{5}\right)\left(2\right)+(2{)}^2$
$=5-4\left(\sqrt{5}\right)+4$
$=9-4\left(\sqrt{5}\right)$