
3个回答
展开全部
1/x-1-2/x²-1
=(x+1)/(x²-1)-2(x²-1)
=(x-1)/(x+1)(x-1)
=1/(x+1)
当x=-2时,原式=1/(-2+1)=-1
=(x+1)/(x²-1)-2(x²-1)
=(x-1)/(x+1)(x-1)
=1/(x+1)
当x=-2时,原式=1/(-2+1)=-1
展开全部
原式=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
=(x+1-2)/(x-1)(x+1)
=(x-1)/(x-1)(x+1)
=1/(x+1)
=1/(-2+1)
=-1
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2013-07-24
展开全部
解:原式=(x+1)/(x^2-1)-2/(x^2-1)=(x+1-2)/(x^-1)=1/(x+1)=1/(-2+1)=-1
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