# Domain range

• Oct 2nd 2009, 07:12 AM
Oasis1993
Domain range
Find the largest possible domain for the following funtions:

a) sqrt x(x-4)

b) sqrt 2x(x-4)

• Oct 2nd 2009, 08:42 AM
redsoxfan325
Quote:

Originally Posted by Oasis1993
Find the largest possible domain for the following funtions:

a) sqrt x(x-4)

b) sqrt 2x(x-4)

So only values of $x$ such that $x(x-4)$ is positive will be in the domain of $\sqrt{x(x-4)}$.
$x(x-4)$ has two zeroes at $x=0$ and $x=4$, so any value of $x:0 will yield a negative value. Thus your domain is $\{-\infty,0]\cup[4,\infty)$.