9-4x^2: I don't know where to begin with this one. There are no examples in the book and no odd numbered similar problems so that I could possibly reverse engineer the problem.
12a^2 +24a: for this one I started with 12(a+1)(a+2). From there I went on to several different variations but came up empty. Wait... is 12a(a+2) the right answer?
Any and all help is much appreciated. Thanks!