先化简,再求值x-1分之1 - x^2-1分之2,其中x=-2 急

chrisnowing 1年前 已收到2个回答 举报
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寻找CC 幼苗

共回答了17个问题采纳率：88.2% 举报

原式=(x+1)/(x+1)(x-1)-2//(x+1)(x-1)
=(x+1-2)/(x+1)(x-1)
=(x-1)/(x+1)(x-1)
=1/(x+1)
=1/(-2+1)
=-1

1年前

7

ranzhang 幼苗

共回答了858个问题 举报

解
1/(x-1)-2/(x²-1)
=(x+1)/(x-1)(x+1)-2/(x²-1)
=(x+1-2)/(x-1)(x+1)
=(x-1)/(x-1)(x+1)
=1/(x+1)
=1/(-2+1)
=-1

1年前

2

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