Let $\mathrm{f}(\mathrm{x})=5-|\mathrm{x}-2|$ and $\mathrm{g}(\mathrm{x})=|\mathrm{x}+1|, \mathrm{x} \in…

Let $\mathrm{f}(\mathrm{x})=5-|\mathrm{x}-2|$ and $\mathrm{g}(\mathrm{x})=|\mathrm{x}+1|, \mathrm{x} \in \mathrm{R}$. If $\mathrm{f}(\mathrm{x})$ attains maximum value at $\alpha$ and $g(x)$ attains minimum value at $\beta$, then $\lim _{x \rightarrow-\alpha \beta} \frac{(x-1)\left(x^2-5 x+6\right)}{\left(x^2-6 x+8\right)}$ is equal to
  1. $\frac{1}{2}$
  2. $\frac{3}{2}$
  3. $-\frac{3}{2}$
  4. $-\frac{1}{2}$

Solution

$\mathrm{f}(\mathrm{x})=5-|\mathrm{x}-2|$ is maximum at $\mathrm{x}=2 \Rightarrow \alpha=2$ $\mathrm{g}(\mathrm{x})=|\mathrm{x}+1|$ is minimum at $\mathrm{x}=-1 \Rightarrow \beta=-1$ Now $\lim _{x \rightarrow-\alpha \beta} \frac{(x-1)\left(x^2-5 x+6\right)}{\left(x^2-6 x+8\right)}=\lim _{x \rightarrow-(2)(-1)} \frac{(x-1)(x-2)(x-3)}{(x-2)(x-4)}$ $\begin{aligned} & =\lim _{x \rightarrow 2} \frac{(x-1)(x-3)}{x-4} \\ & =\frac{(2-1)(2-3)}{2-4} \\ & =\frac{1}{2}\end{aligned}$

Asked in: MHT CET 2022 (05 Aug Shift 1)

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