If $\mathrm{f}(x)=\left(\frac{2^{x}-1}{1-3^{x}}\right)$, for $\mathrm{x} \neq 0$ is continuous at $x=0$,…

If $\mathrm{f}(x)=\left(\frac{2^{x}-1}{1-3^{x}}\right)$, for $\mathrm{x} \neq 0$ is continuous at $x=0$, then $\mathrm{f}(0)=$
  1. $\cdot \log 3$
  2. $\frac{-(\log 2)}{(\log 3)}$
  3. $\frac{(\log 2)}{(\log 3)}$
  4. $-\log 2$

Solution

$f(0)=\lim _{x \rightarrow 0} \frac{2^{x}-1}{-\left(3^{x}-1\right)}=-\frac{\lim _{x \rightarrow 0} \frac{2^{x}-1}{x}}{\lim _{x \rightarrow 0} \frac{3^{x}-1}{x}}=\frac{-\log 2}{\log 3}$ $f(0)=\lim _{x \rightarrow 0} \frac{2^{x}-1}{-\left(3^{x}-1\right)}=-\frac{\lim _{x \rightarrow 0} \frac{2^{x}-1}{x}}{\lim _{x \rightarrow 0} \frac{3^{x}-1}{x}}=\frac{-\log 2}{\log 3}$

Asked in: MHT CET 2020 (20 Oct Shift 1)

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