Let $f(x)=\sqrt{\frac{x}{1-x}}+\sqrt{\frac{1-x}{x}}$. If $\lim _{x \rightarrow m} f(x)=5 / 2$, then set of…

Let $f(x)=\sqrt{\frac{x}{1-x}}+\sqrt{\frac{1-x}{x}}$. If $\lim _{x \rightarrow m} f(x)=5 / 2$, then set of all possible finite values of 1 and $m$ is
  1. $\{0,1\}$
  2. $\left\{0, \frac{1}{3}, \frac{2}{3}\right\}$
  3. $\left\{0, \frac{2}{5}, \frac{3}{5}\right\}$
  4. $\left\{\frac{1}{5}, \frac{4}{5}\right\}$

Solution

$\begin{aligned} & \text { } \lim _{x \rightarrow m} f(x)=\lim _{x \rightarrow m} \sqrt{\frac{x}{1-x}}+\sqrt{\frac{1-x}{x}} \\ & 5 / 2=\lim _{x \rightarrow m} \frac{x+(1-x)}{\sqrt{x(1-x)}}=\lim _{x \rightarrow m} \frac{1}{\sqrt{x-x^2}} \\ & \Rightarrow \quad \frac{5}{2}=\frac{1}{\sqrt{m-m^2}} \Rightarrow 25 m-25 m^2=4 \\ & \Rightarrow 25 m^2-25 m+4=0 \Rightarrow m=\frac{1}{5}, \frac{1}{4}\end{aligned}$

Asked in: AP EAMCET 2023 (19 May Shift 1)

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