已知x+3y=2,求代数式(x²-y²/x+y)-【2(x+y)】的值

已知x+3y=2,求代数式(x²-y²/x+y)-【2(x+y)】的值
已知x+3y=2,求代数式(x²-y²/x+y)-【2(x+y)】的值

已知x+3y=2,求代数式(x²-y²/x+y)-【2(x+y)】的值
原式=[(x+y)(x-y)/(x+y)]-2(x+y)
=x-y-(2x+2y)
=x-y-2x-2y
=-x-3y
=-(x+3y)
=-2

原式=(x+y)(x-y)/(x+y)-2x-2y
=x-y-2x-2y
=-x-3y
=-(x+3y)
=-2

已知x+3y=2
则(x²-y²)/(x+y)-2(x+y)
=x-y-2x-2y
=-x-3y
=-(x+3y)
=-2
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