# What is the domain and range of f(t) = sqrt(9-t)?

$\left\{t : \mathbb{R} , t \le 9\right\}$ 0r $\left(- \infty , 9\right]$
The domain of f(t) would be such that $9 \ge t$ that means t should be less than or equal to 9. This can be expressed as
$\left\{t : \mathbb{R} , t \le 9\right\}$ or $\left(- \infty , 9\right]$