3x^2y-[2xy-2(xy-2/3x^2y)+xy]，其中x=3，y=-3/1.等于
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解决时间 2021-01-31 02:38
- 提问者网友：听门外雪花风
- 2021-01-30 03:42
3x^2y-[2xy-2(xy-2/3x^2y)+xy]，其中x=3，y=-3/1.等于
最佳答案
- 五星知识达人网友：骨子里都是戏
- 2021-01-30 04:54
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
希望能帮到你，祝学习进步
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
希望能帮到你，祝学习进步
全部回答
- 1楼网友：刀戟声无边
- 2021-01-30 06:06
∵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
- 2楼网友：底特律间谍
- 2021-01-30 05:06
解：
3x^2y-[2x^2y-3(2xy-x^2y)-xy]
=3x^2y-2x^2y+3(2xy-x^2y)+xy
=3x^2y-2x^2y+6xy-3x^2y+xy
=3x^2y-3x^2y-2x^2y+6xy+xy
=-2x^2y+7xy
=xy(-2x+7)
=2*(2+7)
=18
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