先化简，再求值：（3/x-2+2/x+2）÷5x²+2x/x²-4，其中x=3
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解决时间 2021-11-14 13:12
- 提问者网友：愿为果
- 2021-11-13 16:10
先化简，再求值：（3/x-2+2/x+2）÷5x²+2x/x²-4，其中x=3
最佳答案
- 五星知识达人网友：第幾種人
- 2021-11-13 17:19
[3/(x-2)+2/(x+2)]÷(5x²+2x)/(x²-4)
=[3/(x-2)+2/(x+2)]*(x²-4)/(5x²+2x)
=[3/(x-2)+2/(x+2)]*(x-2)(x+2)/(5x²+2x)
=3/(x-2)*(x-2)(x+2)/(5x²+2x)+2/(x+2)*(x-2)(x+2)/(5x²+2x)
=3(x+2)/(5x²+2x)+2(x-2)/(5x²+2x)
=[3(x+2)+2(x-2)]/(5x²+2x)
=[3x+6+2x-4]/(5x²+2x)
=[5x+2]/[x(5x+2)]
=1/x
=1/3追问其中x=3 呢？？？追答不是有了吗？追问不是先算（3/x-2+2/x+2）÷5x²+2x/x²-4， 得数算出后 x=3再代入. 真的有吗-我找不到..追答化简得
[3/(x-2)+2/(x+2)]÷(5x²+2x)/(x²-4)
=1/x 代入x=3
=1/3
=[3/(x-2)+2/(x+2)]*(x²-4)/(5x²+2x)
=[3/(x-2)+2/(x+2)]*(x-2)(x+2)/(5x²+2x)
=3/(x-2)*(x-2)(x+2)/(5x²+2x)+2/(x+2)*(x-2)(x+2)/(5x²+2x)
=3(x+2)/(5x²+2x)+2(x-2)/(5x²+2x)
=[3(x+2)+2(x-2)]/(5x²+2x)
=[3x+6+2x-4]/(5x²+2x)
=[5x+2]/[x(5x+2)]
=1/x
=1/3追问其中x=3 呢？？？追答不是有了吗？追问不是先算（3/x-2+2/x+2）÷5x²+2x/x²-4， 得数算出后 x=3再代入. 真的有吗-我找不到..追答化简得
[3/(x-2)+2/(x+2)]÷(5x²+2x)/(x²-4)
=1/x 代入x=3
=1/3
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