Hoặc
b) x3−xy22x2+2xy.
b) x3−xy22x2+2xy=x(x2−y2)2x(x+y)=x(x+y)(x−y)2x(x+y)
=[x(x+y)(x−y)]:[x(x+y)][2x(x+y)]:[x(x+y)]=x−y2.