4x²y-[3xy-2(3xy-2)+2x²y]化简
已知(x+2)²+|y+1|=0,求5xy²-2x²y-[3xy²-(4xy²-2x²y)]急!谢谢...
已知(x+2)²+|y+1|=0,求5xy²-2x²y-[3xy²-(4xy²-2x²y)] 急!谢谢
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(x+2)²+|y+1|=0 两个非负数的和为零 他们都是零
x+2=0 y+1=0
x=-2 y=-1
5xy²-2x²y-[3xy²-(4xy²-2x²y)]
=5xy²-2x²y-[3xy²-4xy²+2x²y]
=5xy²-2x²y-3xy²+4xy²-2x²y
=5xy²-3xy²+4xy²-2x²y-2x²y
=(5-3+4)xy²-4x²y
=6xy²-4x²y
=2xy(3y-2x)
=2×2×(-3+4)
=4
x+2=0 y+1=0
x=-2 y=-1
5xy²-2x²y-[3xy²-(4xy²-2x²y)]
=5xy²-2x²y-[3xy²-4xy²+2x²y]
=5xy²-2x²y-3xy²+4xy²-2x²y
=5xy²-3xy²+4xy²-2x²y-2x²y
=(5-3+4)xy²-4x²y
=6xy²-4x²y
=2xy(3y-2x)
=2×2×(-3+4)
=4
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