A cura di: Francesco Speciale

Svolgimento:
$3x^3y-[-(x+2x)(3/2x)(-1/3xy)+2x(xy)(-1/2x)]-[-5x(-xy)(-x)]=$
$=3x^3y-[-(9/2x^2)(-1/3xy)+(2x^2y)(-1/2x)]-[-5x(x^2y)]=$
$=3x^3y-[3/2x^3y-x^3y]+5x^3y=$
$3x^3y-(1/2x^3y)+5x^3y=((6-1+10)/2)x^3y=(15)/2x^3y$.