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lim(x->e) (lnx-1)/(x-e) (0/0)
= lim(x->e) (1/x)/1
=1/e
or
expands lnx about e
lnx = lne +(x-e)/e + (x-e)^2/e^2+...
= 1+(x-e)/e + (x-e)^2/e^2+...
(lnx-1)/(x-e)
= [ 1+(x-e)/e + (x-e)^2/e^2+...- 1] /(x-e)
= ((x-e)/e + (x-e)^2/e^2+.)/(x-e)
= 1/e + (x-e)/e^2 + (x-e)^2/e^3 +...
lim(x->e)(lnx-1)/(x-e)
=lim(x->e)[1/e + (x-e)/e^2 + (x-e)^2/e^3 +...]
=1/e
1年前
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