Hoặc
g) 3y−2xx−2y−x−y2y−x.
g) 3y−2xx−2y−x−y2y−x=3y−2xx−2y+x−yx−2y
=3y−2x+x−yx−2y=2y−xx−2y=−x−2yx−2y=−1.