Math Is Fun Forum

Núria

Guest

limit of a logarithm

I would like to know, if the limit of a logarithmic funcation, lim(log(x)), when x --> infinity, is log(lim(x)) when x--> infinty, due to the logarithmic function behavior.

Thanks!
Núria

núria

Guest

Re: limit of a logarithm

I would like to know, if the limit of a logarithmic funcation, lim(log(ax/bx+c)), when x --> infinity, is log(lim(ax/bx+c)) when x--> infinty, due to the logarithmic function behavior.
Thanks!
Núria

Flowers4Carlos

Member

Registered: 2005-08-25

Posts: 106

Re: limit of a logarithm

hi there Nuu.... uu... ria!!!

just for reference reasons, here is the graph of logx :

as we can see, logx will go to ∞ when x gets larger and larger.  but ∞ is not a number and consequently we cannot evaluate log(∞).  however, if we know what happens to x as it approaches ∞, we can easily compute the limit of logt.  here is how:

           lim(x->∞ ) logx
                    as x -> ∞, we know t = x -> (∞) = ∞
           lim(t->∞ )logt = ∞

hope this helps!!!