来自朗勇的问题
数学求代数式的值(x-2y)(x+2y)-(x+y)(x-y)+3y的2次-x+y-1
数学求代数式的值
(x-2y)(x+2y)-(x+y)(x-y)+3y的2次-x+y-1
1回答
2019-04-26 06:20
数学求代数式的值(x-2y)(x+2y)-(x+y)(x-y)+3y的2次-x+y-1
数学求代数式的值
(x-2y)(x+2y)-(x+y)(x-y)+3y的2次-x+y-1
(x-2y)(x+2y)-(x+y)(x-y)+3y²-x+y-1
=x²-4y²-x²+y²+3y²-x+y-1
=-x+y-1