Question

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

Answer 1

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

$⟹9-x^2\ge 0$

$⟹x^2-9\le 0$

$⟹x\in [-3,3]$

The domain of $f\left(x\right)$ is $[-3,3]$