1. 1 / x-1 - 1 / x+1
2. 1/ 1-x^2 - 1 / (1+x)^2
數學------中一 (請教)
2010-02-11 1:56 am
回答 (2)
2010-02-11 2:55 am
✔ 最佳答案
1. 1 / (x-1) - 1 / (x+1)= (x+1) / [(x-1)(x+1)] - (x-1) / [(x+1)(x-1)]
= [ (x+1) - (x-1) ] / [(x-1)(x+1)]
= 2 / [(x-1)(x+1)]
2. 1 / (1-x^2) - 1 / (1+x)^2
= 1 / [(1-x)(1+x)] - 1 / (1+x)^2
= (1+x) / [(1-x)(1+x)^2] - (1-x) / [(1-x)(1+x)^2]
= [ (1+x) - (1-x) ] / [(1-x)(1+x)^2]
=2x / [(1-x)(1+x)^2]
收錄日期: 2021-04-21 22:08:05
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100210000051KK01073