f(x)=(x³-4x)(7x⁴+5x-1)

f⁾(x)=((x³-4x)(7x⁴+5x-1))⁾=(3x²-4)(7x⁴+5x-1) + (x³-4x)(28x³+5) =

=21x⁶+15x³-3x²-28x⁴-20x+4 +28x⁶+5x³- 112x⁴-20x = 49x⁶-140x⁴+20x³-3x²-40x+4