这11道题是否正确，后三道分别是x=10 x=10/3，y=8/3 x=-28，y=18
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7（p³+p²-p-1)-2(p³+p)
=7p³+7p²-7p-7-2p³-2p
=7p³-2p³+7p²-7p-2p-7
=5p³+7p²-9p-7
-(x²y+3xy-4)+3(x²y-xy+2)
=-x²y-3xy+4+3x²y-3xy+6
=-x²y+3x²y-3xy-3xy+6+4
=2x²y-6xy+10
(xy-3/2y-1/2)-(xy-3/2x+1)
=xy-3/2y-1/2-xy+3/2x-1
=xy-xy-3/2y-1/2-1+3/2x
=-3/2y-3/2+3/2x
当x=10/3,y=8/3,代入原式，
得-3/2×8/3-3/2+3/2×10/3=15/2
=7p³+7p²-7p-7-2p³-2p
=7p³-2p³+7p²-7p-2p-7
=5p³+7p²-9p-7
-(x²y+3xy-4)+3(x²y-xy+2)
=-x²y-3xy+4+3x²y-3xy+6
=-x²y+3x²y-3xy-3xy+6+4
=2x²y-6xy+10
(xy-3/2y-1/2)-(xy-3/2x+1)
=xy-3/2y-1/2-xy+3/2x-1
=xy-xy-3/2y-1/2-1+3/2x
=-3/2y-3/2+3/2x
当x=10/3,y=8/3,代入原式，
得-3/2×8/3-3/2+3/2×10/3=15/2
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