Question 156686
Well notice how if {{{x=3}}}, then {{{f(3)=1/((3)^2-9)=1/(9-9)=1/0}}} which is <b>NOT</b> defined. Also, if {{{x=-3}}}, then {{{f(3)=1/((-3)^2-9)=1/(9-9)=1/0}}} which is also <b>NOT</b> defined. So that's why there are domain restrictions of {{{x<>-3}}} and {{{x<>3}}}