Hoặc
d) x+2y4x−24xy+y2 . (2x−y).
d) x+2y4x−2 4xy+y2 . (2x−y)=x+2y(2x−y)2 . (2x−y)
=(x+2y)(2x−y)(2x−y)2=x+2y2x−y.