Hi, this question is giving me a really hard time:

With it, I'm supposed to: identify critical points, inflection points, asymptotes, where it is increasing, and where it is decreasing. I'm not really having a problem with the first three (I already found inflection points to be "none", as well as critical points), but I don't know how to find intervals of increase and decrease or intervals of concavity without having critical points or inflection points. I tried just looking at the first derivative, which I got to be 25/(x+6)^2) and reasoning that an x value above -6 would lead to increase, and below -6 would lead to decrease. This didn't work (although it did get me the vertical asymptote x=-6).

I'd really appreciate help on this question. Thanks!