Rút gọn các biểu thức sau: (x−2y)^3 −(x+2y) (x^2 −2xy+4y^2) +6x^2 y
Giải thích
x−2y3−x+2yx2−2xy+4y2+6x2y=x3−3.x2.2y+3.x.2y2−2y3−x+2yx2−2xy+2y2+6x2y=x3−6x2y+12xy2−8y3−x3+8y3+6x2y=x3−6x2y+12xy2−8y3−x3−8y3+6x2y=12xy2−16y3
x−2y3−x+2yx2−2xy+4y2+6x2y=x3−3.x2.2y+3.x.2y2−2y3−x+2yx2−2xy+2y2+6x2y=x3−6x2y+12xy2−8y3−x3+8y3+6x2y=x3−6x2y+12xy2−8y3−x3−8y3+6x2y=12xy2−16y3