Question

Solve:

$f\left(x\right)=\sqrt{9-x^2}=0$

Answer 1

$f\left(x\right)=\sqrt{9-x^2}$

Now $\sqrt{9-x^2}$

$\Rightarrow (\sqrt{9-x^2}{)}^2=0^2=0$

$\Rightarrow x^2-9=0$

$\Rightarrow x^2=9$

$\Rightarrow x=\pm 3$.

$\therefore x=+3$ or $x=-3$