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-2分之1x-(x-3)

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-2分之1x-(x-3)
-2分之1(4x-6)+3分之1(6-3x)
-(x的平方-2x-2)+2(x的平方-1)
2n-(2-n)+(6n-2)
(a的平方b-ab)-2(ab的平方-ba)【先化简再求值】其中a= -2分之1.b=2
(a-ab)+(b+2ab)-(a+b)【化简再求值】a=7.b= -7分之1

-1/2x-(x-3)
=-1/2x-x+3
=-3/2x+3
-1/2(4x-6)+1/3(6-3x)
=-2x+3+2-x
=-3x+5
-(x²-2x-2)+2(x²-1)
=-x²+2x+2+2x²-2
=x²+2x
2n-(2-n)+(6n-2)
=2n-2+n+6n-2
=9n-4
(a²b-ab)-2(ab²-ba)
=a²b-ab-2ab²+2ab
=a²b-2ab²+ab
=ab(a-2b+1)
=-(-1/2-4+1)
=7/2
(a-ab)+(b+2ab)-(a+b)
=a-ab+b+2ab-a-b
=ab=7×(-1/7)=-1