Joey's question
If r(x)=(Ax^B + Cx^D)(Ex^F - Gx^H) find r'(x)
r'(x)=(ABx^(B-1) + CDx^(D-1))(Ex^F - Gx^H) + (EFx^(F-1) - GHx^(H-1))(Ax^B + Cx^D)