I need to find the range of f(x)=(x^2-8)/(x+3) and use f'(x) to justify my answer. I found f'(x) to be (x^2+6x+8)/(x+3)^2 and I found the critical numbers of f to be -4,-3,-2, but I don't know where to go from here. By looking at the graph the range looks like its (-inf,-8)(-4,+inf) but I don't know how to prove that algebraically. Please Help!