limx趋于1(x/x-1)/(1/lnx)

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limx趋于1(x/x-1)/(1/lnx)

limx趋于1(x/x-1)/(1/lnx)
limx趋于1(x/x-1)/(1/lnx)

limx趋于1(x/x-1)/(1/lnx)
当x-->1时,lnx=ln(1+x-1)与x-1等价,所以利用等价无穷小的替换得
lim(x-->1)[x/(x-1)] /(1/lnx)=lim(x-->1)(xlnx)/(x-1)
=lim(x-->1)(x(x-1))/(x-1) =lim(x-->1)x=1.

x/x-1=1+1/(x-1)所以原式等于(1+1/(x-1))/(1/lnx)=lnx+lnx/(x-1)当x~1时lnx~0;lnx/(x-1)罗比达法则~(1/x)/1~1/x~1所以最后结果就是1

lim_{x->1}{[x/(x-1)]/[1/ln(x)]}
=lim_{x->1}[xln(x)/(x-1)]
=lim_{x->1}{[1+ln(x)]/1}
=1