y‘=[(2x+1)^3]'*(3-4x)^5+(2x+1)^3*[(3-4x)^5]'=3(2x+1)^2*(2x+1)'*(3-4x)^5+(2x+1)^3*5(3-4x)^4*(3-4x)'=3(2x+1)^2*2*(3-4x)^5+(2x+1)^3*5(3-4x)^4*(-4)=6(2x+1)^2*(3-4x)^5-20(2x+1)^3*(3-4x)^4=-(2x+1)^2*(3-4x)^4(64x-2)
