How do you simplify sqrt7 - sqrt63 ?

Jan 29, 2017

$= - 2 \sqrt{7}$

Explanation:

$\sqrt{7} - \sqrt{63} \text{ } \leftarrow$ write 63 as the product of factors

$= \sqrt{7} - \sqrt{3 \times 3 \times 7} \text{ } \leftarrow \sqrt{{3}^{2}} = 3$

$= \sqrt{7} - 3 \sqrt{7} \text{ } \leftarrow 1 - 3 = - 2$

$= - 2 \sqrt{7}$