先化简,在求(x/x-2-x/2+x)除以4x/2-x的值,其中x=-1/2
答案:2 悬赏:30 手机版
解决时间 2021-02-10 04:06
- 提问者网友：太高姿态
- 2021-02-09 07:07
先化简,在求(x/x-2-x/2+x)除以4x/2-x的值,其中x=-1/2
最佳答案
- 五星知识达人网友：掌灯师
- 2021-02-09 07:37
x/(x-2)-x/(2+x)除以4x/(2-x)
=[x(x+2)/(x-2)(x+2) -x(x-2)/(x-2)(x+2)]乘以(2-x)/4x
=[(x^2+2x-x^2+2x)/(x-2)(x+2)]乘以(2-x)/4x
= 4x/(x-2)(x+2)]乘以(2-x)/4x
= -(x+2)
= -x-2
= -(-1/2)-2
= -3/2
=[x(x+2)/(x-2)(x+2) -x(x-2)/(x-2)(x+2)]乘以(2-x)/4x
=[(x^2+2x-x^2+2x)/(x-2)(x+2)]乘以(2-x)/4x
= 4x/(x-2)(x+2)]乘以(2-x)/4x
= -(x+2)
= -x-2
= -(-1/2)-2
= -3/2
全部回答
- 1楼网友：千夜
- 2021-02-09 08:25
[x/(x-2)-x/(x+2)]×[-(x-2)/4x]
=[x(x+2)-x(x-2)] /(x+2)(x-2)×[-(x-2)/4x]
=4x/(x+2)(x-2)×[-(x-2)/4x]
=-1/(x+2)
当x=-1/2时
原式=-1/(-1/2+2)
=-2/3
=[x(x+2)-x(x-2)] /(x+2)(x-2)×[-(x-2)/4x]
=4x/(x+2)(x-2)×[-(x-2)/4x]
=-1/(x+2)
当x=-1/2时
原式=-1/(-1/2+2)
=-2/3
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