Question 817077
Careful!  If you simplify the expression, then that is a different function.
{{{r(x)=(9x^2-36)/(x+2)}}}

{{{(9x^2-36)/(x+2)}}}
{{{(9*(x^2-4))/(x+2)}}}
{{{r(x)=9((x+2)(x-2))/(x+2)}}}
As simplifed,
{{{f(x)=9(x-2)}}}


r(x) and f(x) are different functions.
One is rational and the other is a line.
r(x) is undefined at {{{x=-2}}};
the domain for r(x) is {{{x<-2}}} and {{{x>-2}}}