题目内容
已知:|x-2|+|y+1|=0,求5xy2-2x2y+[3xy2-(4xy2-2x2y)]的值.
∵|x-2|+|y+1|=0,
∴x-2=0,y+1=0,
解得x=2,y=-1,
原式=5xy2-2x2y+3xy2-4xy2+2x2y,
=4xy2,
=4×2×1,
=8.
∴x-2=0,y+1=0,
解得x=2,y=-1,
原式=5xy2-2x2y+3xy2-4xy2+2x2y,
=4xy2,
=4×2×1,
=8.
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