# How do you add 13\sqrt { 21x ^ { 13} } + 10\sqrt { 21x ^ { 13} }?

Nov 16, 2017

$23 \sqrt{21 {x}^{13}}$

#### Explanation:

There's a common factor $\sqrt{21 {x}^{13}}$ which we can take out,
$\sqrt{21 {x}^{13}} \left(13 + 10\right)$

as $13 + 10 = 23$ we can simplify,
$\sqrt{21 {x}^{13}} \left(23\right)$

and we write it "correctly",
$23 \sqrt{21 {x}^{13}}$