# How do you find the domain of f (x)= sqrt(-5x-10)?

Nov 4, 2017

Domain: $x \le - 2$

#### Explanation:

Assuming we are restricted to Real values
$\sqrt{- 5 x - 10}$
is only defined if #(-5x-10) >= 0

that is only if
$\textcolor{w h i t e}{\text{XXXX}} \left(- 10\right) \ge 5 x$ (after adding $5 x$ to both sides)

or
$\textcolor{w h i t e}{\text{XXXX}} - 2 \ge x$ (after dividing both sides by $5$)