Hoặc
b) x3+y3x−y:(x2−xy+y2).
b) x3+y3x−y:(x2−xy+y2)
=(x+y)(x2−xy+y2)x−y . 1x2−xy+y2
=(x+y)(x2−xy+y2)(x−y)(x2−xy+y2)=x+yx−y.