4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²,其中x=2,y=-3

4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²,其中x=2,y=-3
4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²,其中x=2,y=-3

4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²,其中x=2,y=-3
4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²,其中x=2,y=-3
=4x²y-1/2x²y+1/2(5x²y-4xy²-1/2xy)+3xy²
=7/2x²y+5/2x²y-2xy²-1/4xy+3xy²
=6x²y-1/4xy+xy²
=6*2²*(-3)-1/4*2*(-3)+2*(-3)²
=-72+3/2+18
=--52又2分之1

x+y=2-3= -1
4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²
=4x²y-1/2[x²y-5x²y+2(2xy²+1/4xy)]+3xy²
=4x²y-1/2[-4x²y+4xy²+1/2xy]+3xy&...

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x+y=2-3= -1
4x²y-1/2{x²y-[5x²y-2(2xy²+1/4xy)]}+3xy²
=4x²y-1/2[x²y-5x²y+2(2xy²+1/4xy)]+3xy²
=4x²y-1/2[-4x²y+4xy²+1/2xy]+3xy²
=4x²y+2x²y-2xy²-1/4xy+3xy²
=6x²y-1/4xy+xy²
=5x²y-1/4xy+xy(x+y)
=5x²y-5/4xy
=5xy(x-1/4)
=5*2*(-3)*(2-1/4)
= -105/2

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