已知x+y=-2,xy=-1,求x+1分之y+1+y+1分之x+1的值!快点哦,我加分!
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解决时间 2021-01-28 07:55
- 提问者网友：贪了杯
- 2021-01-27 14:15
已知x+y=-2,xy=-1,求x+1分之y+1+y+1分之x+1的值!快点哦,我加分!
最佳答案
- 五星知识达人网友：独行浪子会拥风
- 2021-01-27 15:37
x+1分之y+1+y+1分之x+1
=(y+1)/(x+1)+(x+1)/(y+1)
=(y²+2y+1+x²+2x+x)/(x+1)(y+1)
=(x²+2xy+y²-2xy+2x+2y+2)/(xy+x+y+1)
=[(x+y)²-2xy+2(x+y)+2]/(xy+x+y+1)
=[(-2)²-2*(-1)+2*(-2)+2]/(-2-1+1)
=(4+2-4+2)/(-2)
=4/(-2)
=-2
=(y+1)/(x+1)+(x+1)/(y+1)
=(y²+2y+1+x²+2x+x)/(x+1)(y+1)
=(x²+2xy+y²-2xy+2x+2y+2)/(xy+x+y+1)
=[(x+y)²-2xy+2(x+y)+2]/(xy+x+y+1)
=[(-2)²-2*(-1)+2*(-2)+2]/(-2-1+1)
=(4+2-4+2)/(-2)
=4/(-2)
=-2
全部回答
- 1楼网友：怀裏藏嬌
- 2021-01-27 17:09
第一种：x+y=6,xy=4所以y=4/x
x+4/x=6 解得x代入
第二种通分
为x^2+y^2+2(x+y)+2/ xy+x+y+1
x^2+y^2=(x+y)^2-2xy
代入x+y=6,xy=4
- 2楼网友：白昼之月
- 2021-01-27 17:00
=[(y+1)²+(x+1)²]/(x+1)(y+1)
=(x²+y²+2x+2y+2)/(xy+x+y+1)
=[(x+y)²-2xy+2(x+y)+2]/[xy+(x+y)+1]
=(4+2-4+2)/(-1-2+1)
=4/(-2)
=-2
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