The set of all real values of $x$ for which the real valued function $f(x)=\left(1+\frac{1}{x}\right)^x$ is…

The set of all real values of $x$ for which the real valued function $f(x)=\left(1+\frac{1}{x}\right)^x$ is defined, is
  1. $(0, \infty)$
  2. $R-\{0\}$
  3. $(-\infty,-1) \cup(0, \infty)$
  4. $R-\{0,-1\}$

Solution

$\begin{array}{ll}& f(x)=\left(1+\frac{1}{x}\right)^x \\ \Rightarrow & \left(1+\frac{1}{x}\right)>0 \\ & \frac{x+1}{x}>0 \\ & \frac{-1+1}{-1} \\ \Rightarrow & x \in(-\infty,-1) \cup(0, \infty) .\end{array}$

Asked in: AP EAMCET 2018 (24 Apr Shift 1)

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