Medium MCQ +4 / -1 PYQ · JEE Mains 2025

Let the function $f(x)=\left(x^2-1\right)\left|x^2-a x+2\right|+\cos |x|$ be not differentiable at the two points $x=\alpha=2$ and $x=\beta$. Then the distance of the point $(\alpha, \beta)$ from the line $12 x+5 y+10=0$ is equal to :

  1. A <p>5</p>
  2. B <p>2</p>
  3. C 4
  4. D <p>3</p> Correct answer

Solution

<p>$\cos |\mathrm{x}|$ is always differentiable</p> <p>$\therefore$ we have to check only for $\left|\mathrm{x}^2-\mathrm{ax}+2\right|$</p> <p>$\therefore$ Not differentiable at</p> <p>$x^2-a x+2=0$</p> <p>One root is given, $\alpha=2$</p> <p>$$\begin{aligned} \therefore \quad 4 & -2 a+2=0 \\ & a=3 \end{aligned}$$</p> <p>$\therefore$ other root $\beta=1$</p> <p>but for $x=1 f(x)$ is differentiable</p> <p>(Drop)</p>

About this question

Subject: Mathematics · Chapter: Limits, Continuity and Differentiability · Topic: Limits and Standard Results

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