Do can you tell when you can use the substitution method? I just tried it on $\displaystyle \int_{-1}^0(2x+3)^2dx$, but I don't get the right answer unless I square the $\displaystyle (2x+3)$ and then proceed normally.

What about substitution on $\displaystyle \int_3^2\frac{x^2-1}{x-1}dx$?