I'm fairly sure I discovered a bug with the Maple 17 Calculus Integration tutor.

I was working on int((x^2+2*x)*cos(x), x);.

The first step that the tutor wants you to do is to rewrite the integral by factoring out an x from the first term, and changing cos(x) to -sin(x).

The next step is to rewrite it again, this time changing sin to cos, making the intergal  -x(x+2)cos(x)

Next, the tutor distributes the X again, making the integral -(x^2+2*x...