$\lim _{x \rightarrow 0} \frac{4^x-9^x}{x\left(4^x+9^x\right)}$ is equal to

$\lim _{x \rightarrow 0} \frac{4^x-9^x}{x\left(4^x+9^x\right)}$ is equal to
  1. $\log \frac{2}{3}$
  2. $\log \frac{3}{2}$
  3. $\frac{1}{2} \log \frac{2}{3}$
  4. $\frac{1}{2} \log \frac{3}{2}$

Solution

We have, $ \lim _{x \rightarrow 0} \frac{4^x-9^x}{x\left(4^x+9^x\right)} $ Using L-Hospital's rule $ \begin{aligned} & =\lim _{x \rightarrow 0} \frac{4^x \log 4-9^x \log 9}{\left(4^x+9^x\right)+x\left(4^x \log 4+9^x \log 9\right)} \\ & =\frac{\log 4-\log 9}{2}=\frac{2 \log \frac{2}{3}}{2}=\log \frac{2}{3} \end{aligned} $

Asked in: AP EAMCET 2002

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