Question

I need help solving this radical operation$\sqrt{90} - \sqrt{40}$

Answer 1

$\begin{gathered} \sqrt{90}-\sqrt{40}=\sqrt{9\times10}-\sqrt{4\times10} \\ \text{ =}\sqrt{9}\times\sqrt{10}-\sqrt{4}\times\sqrt{10} \\ \text{ =3}\sqrt{10}-2\sqrt{10} \end{gathered}$

taking √10 common,

$\sqrt{10}(3-2)=\sqrt{10}$