如果(3x²-2)-(3x²-y)=-2,那么代数式(x+y)+3(x-y)-4(x-y-2)的值是

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如果(3x²-2)-(3x²-y)=-2,那么代数式(x+y)+3(x-y)-4(x-y-2)的值是
如果(3x²-2)-(3x²-y)=-2,那么代数式(x+y)+3(x-y)-4(x-y-2)的值是

如果(3x²-2)-(3x²-y)=-2,那么代数式(x+y)+3(x-y)-4(x-y-2)的值是
(3x²-2)-(3x²-y)=-2
3x²-2-3x²+y=-2
y-2=-2
y=0
(x+y)+3(x-y)-4(x-y-2)
=x+y+3x-3y-4x+4y+8
=2y+8
=0+8
=8
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(3x²-2)-(3x²-y)=-2
3x²-2-3x²+y=-2
y=0
(x+y)+3(x-y)-4(x-y-2)
=x+y+3x-3y-4x+4y+8
=2y+8
=0+8
=8

将前式括号打开,3x^2被消掉了,可知y=0。那么将后式中括号打开,原式=x+y+3x-3y-4x+4y+8=2y+8=8
所以值为8