Question 447880
{{{f(x)  = (x+5)/(x^2+2x-15) = (x+5)/((x+5)(x-3)) = 1/(x-3)}}}, {{{x<>-5}}}
Hence the domain is the set of all real numbers except 3, -5.
(There is a vertical asymptote x = 3.  There is a "hole" on the graph at the point (-5, -1/8).)