Just a note: Sometimes getting rid of unnecessary parentheses may help in searches. Here's a query for $\displaystyle\lim_{x\to-\ìnfty}(\frac{\ln(2^x+1)}{\ln(3^x+1)})$ which yields no result,
and here's one for $\displaystyle\lim_{x\to-\ìnfty}\frac{\ln(2^x+1)}{\ln(3^x+1)}$ which finds a question.
