# [MOVED] find domain of f(x) = (x + 10)/(x^2 - 289)

#### linfinity27

##### New member
f(x) = (x + 10)/(x^2 - 289)

I need to figure out the domain, and I'm stuck! Thanks in advance for the help!

#### soroban

##### Elite Member
Re: domain of a function

Hello, linfinity27!

Find the domain of: $$\displaystyle \,f(x)\:=\:\frac{x\,+\,10}{x^2\,-\,289}$$

Recall that the domain cannot include values which make the denominator equal to zero.

This denominator is zero when: $$\displaystyle x^2\,-\,289\:=\:0\;\;\Rightarrow\;\;x^2\:=\:289\;\;\Rightarrow\;\;x\:=\:\pm17$$

Therefore, the domain is: all real numbers except 17 and -17.