Wednesday, June 24, 2015

Find the limit of function f(x) given by f(x)=ln(x-1)/(x-2), x->2?

First, we'll substitute x by the value of accumulation
point.


lim ln(x-1)/(x-2) = ln(2-1)/(2-2) = ln1/0 =
0/0


We've get an indetermination, so, we'll apply
L'Hospital rule:


lim ln(x-1)/(x-2) = lim
d[ln(x-1)]/dx/d(x-2)/dx


lim d[ln(x-1)]/dx/d(x-2)/dx = lim
1/(x-1)/1


We'll substitute again x by 2 and we'll
get:


lim 1/(x-1)/1 = 1/(2-1) =
1


The limit of the function f(x) is lim
ln(x-1)/(x-2) = 1.

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