## Intermediate Algebra (12th Edition)

The given equation $\sqrt{3x+18}=x ,$ cannot have a negative solution since the left side of the equal sign is always a non negative number. Since the left side is equal to $x$, then $x$ cannot be a negative number.
$\bf{\text{Solution Outline:}}$ Use the fact that taking the even root of a non negative number is a positive number. $\bf{\text{Solution Details:}}$ The given equation $\sqrt{3x+18}=x ,$ cannot have a negative solution since the left side of the equal sign is always a non negative number. Since the left side is equal to $x$, then $x$ cannot be a negative number.