The quadratic equation whose roots are $m$ and $n$, where $m=\lim _{x \rightarrow 0} \frac{x \log (1+2 x)}{x…

The quadratic equation whose roots are $m$ and $n$, where $m=\lim _{x \rightarrow 0} \frac{x \log (1+2 x)}{x \tan x}$ and $n=\lim _{x \rightarrow 0} \frac{\log x+\log \left(\frac{(1+x)}{x}\right)}{x}$, is
  1. $x^2-x+2=0$
  2. $x^2-3 x+2=0$
  3. $x^2+x+2=0$
  4. $x^2+3 x+2=0$

Solution

$\begin{aligned} & m=\lim _{x \rightarrow 0} \frac{x \log (1+2 x)}{x \cdot \tan x}=\lim _{x \rightarrow 0} \frac{\frac{\log (1+2 x)}{2 x} \cdot 2 x}{\frac{\tan x}{x} \cdot x}=2 \\ & n=\lim _{x \rightarrow 0} \frac{\log x+\log \left(\frac{1+x}{x}\right)}{x}=\lim _{x \rightarrow 0} \frac{\log \left(x \times \frac{1+x}{x}\right)}{x} \\ & =\lim _{x \rightarrow 0} \frac{\log (1+x)}{x}=1\end{aligned}$ now, required quadratic equation is $x^2-(m+n) x+m n=0$ $\Rightarrow x^2-3 x+2=0$

Asked in: MHT CET 2022 (10 Aug Shift 2)

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