学帮网化简求值:3x²y-[2xy-2(xy-3/2x²y)+xy],其中x=3,y=-1/3如题
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化简求值:3x²y-[2xy-2(xy-3/2x²y)+xy],其中x=3,y=-1/3
如题
3x²y-[2xy-2(xy-3/2x²y)+xy]
=3x²y-2xy+2(xy-3/2x²y)+xy
=3x²y-2xy+2xy-3x²y+xy
=xy
=3×（-1/3）
=-1
3x²y-[2xy-2(xy-3/2x²y)+xy]
= 3x²y - [2xy - 2xy + 3x²y + xy]
= 3x²y - (3x²y + xy)
= - xy
= 1