3x^2y-[2xy-2(xy-2/3x^2y)+xy],其中x=3,y=-3/1.等于
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发布时间:2024-10-09 03:15
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热心网友
时间:2024-11-14 04:36
先化简,再求值
3x²y-[2xy-2(xy-2/3x²y)+xy]
=3x²y-2xy+2(xy-2/3x²y)-xy
=3x²y-2xy+2xy-4/3x²y-xy
=5/3x²y-xy
=xy(5/3x-1)
将x=3,y=-1/3 代入
原式=xy(5/3x-1)=3×(-1/3)(5/3×3-1)=-1×(5-1)=-4
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热心网友
时间:2024-11-14 04:39
∵x=3,y=-3/1(此处应为:y=-1/3)
3x^2y-[2xy-2(xy-2/3x^2y)+xy]=3x²y-2xy+2xy-4x²y/3-xy=5x²y/3-xy=5×3²×(-1/3)/3-3×(-1/3)=-5+1=-4
热心网友
时间:2024-11-14 04:39
3x²y-[2xy-2(xy-2/3x²y)+xy]
=3x²y﹣3x²y﹣xy
=﹣xy
=﹣3×﹙﹣1/3﹚
=1