What is (2x-3)(x+4)Q(x)+b in terms of x?
It can be re-written like this:
b+2 x^2 Q(x)+5 x Q(x)-12 Q(x)
Derivative:(d)/(dx)(b+(x+4) (2 x-3) Q(x)) = (2 x^2+5 x-12) Q'(x)+(4 x+5) Q(x)
