先化简再求值x/x²-1(x-1/x-2)
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先化简再求值x/x²-1(x-1/x-2)先化简再求值x/x²-1(x-1/x-2)先化简再求值x/x²-1(x-1/x-2)=x/(x+1)(x-1)×(x-1-2x)
先化简再求值x/x²-1(x-1/x-2)
先化简再求值x/x²-1(x-1/x-2)
先化简再求值x/x²-1(x-1/x-2)
=x/(x+1)(x-1) ×(x-1-2x)/x
=x/(x+1)(x-1)×[-(x+1)/x]
=-1/(x-1)
=1/(1-x)
当x=2时
原式=1/(1-2)=-1