(2x-y)²-4(x-y)(x+2y) =4x²-4xy+y²-4(x²+xy-2y²)=4x²-4xy+y²-4x²-4xy+8y²=9y²-8xy=y(9y-8x)
9y2-8xy 采纳谢谢
(2x-y)²-4(x-y)(x+2y) =4x²-4xy+y² -4(x²+ 2xy-xy+2y²)= 4x²-4xy+y² - 4(x² + xy+2y²)= 4x²-4xy+y²-4x²-4xy-8y²= -8xy-7y²=-y(8x+7y)