Question

先化简再求值：(x+y)(x-y)+(x-y)方-(6x方y-2xy方)÷2y,其中x=-2,y=3分之1【过程+答案，谢谢】

Answer 1

(x+y)(x-y)+(x-y)方-(6x方y-2xy方)÷2y
=(x-y)(x+y+x-y) - 2xy(3x-y)÷(2y)
=2x(x-y) - x(3x-y)
=x(2x-2y -3x+y)
=x(-x-y)
=-x(x+y)
已知x=-2,y=3分之1，那么：
原式=-x(x+y)=-(-2)*(-2+ 3分之1)=2*(-3分之5)=-3分之10

Answer 2

解： 原式=x^2-y^2+x^2-2xy+y^2-3x^2+2x
=-x^2-2xy+2x
将代x=-2,，y=1/3人上式得
-4+4/3-4=-20/3

Answer 3

原式=x^2-y^2+x^2-2xy+y^2-3x^2+2x
=2x(x-y) - x(3x-y)
=x(2x-2y -3x+y)
=-x(x+y)