# Math Help - simplifying under a radical

1. ## simplifying under a radical

Can

$\sqrt{9-x^2}$

be simplified to

$3-x$

?

2. No, because $9-x^2=(3-x)(3+x)$
So $\sqrt{9-x^2}=\sqrt{(3-x)(3+x)}$

You can even put in a number to test.
Let $x=1$

For $x=1$
$\sqrt{9-x^2}=2\sqrt{2}$
While
$3-x=2$