Let the function f(x) = (x^2 - 1)|x^2 - ax + 2| + 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 12x + 5y + 10 = 0 is equal to:

Solution & Explanation

### Core Logic The expression cos|x| is everywhere differentiable. Thus, non-differentiability relies completely on the modulus function containing the quadratic factor, i.e., |x^2 - ax + 2|. Non-differentiability points generally happen where: x^2 - ax + 2 = 0 ### Step 1: Evaluation of Roots Given one of the roots is alpha = 2: 2^2 - a(2) + 2 = 0 implies 6 - 2a = 0 implies a = 3 Substituting a=3 gives the other root beta = 1. However, evaluating differentiability at x=1 reveals properties that invalidate standard options. ### Step 2: Conclusion Due to a technical contradiction in the configuration of the differentiable constraints at x=1, this question was officially dropped by NTA. ### Pattern Recognition If a quadratic inside a modulus has distinct real roots, it normally creates non-differentiable sharp turns unless a repeated multiplying factor outside cancels it out. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Limits, Continuity and Differentiability

Reference Study Guides

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Q17 jee_main_2024_31_jan_morning Continuity Check
Let g(x) be a linear function and f(x) = begincases g(x) & , x le 0 \\ left(frac1+x2+xright)^frac1x & , x > 0 endcases is continuous at x = 0. If f'(1) = f(-1), then the value of g(3) is
  • A. frac13 log_e left(frac49e^1/3right)
  • B. frac13 log_e left(frac49right) + 1
  • C. log_e left(frac49right) - 1
  • D. log_e left(frac49e^1/3right)

Solution

### Core Logic Let g(x) = ax + b. Since f(x) is continuous at x = 0: lim_x to 0^+ f(x) = f(0) lim_x to 0 left(frac1+x2+xright)^frac1x = b As x to 0, the base approaches frac12, and exponent approaches infty. Thus, left(frac12right)^infty = 0. So, b = 0. Thus, g(x) = ax. ### Step 1: Calculate Derivative For x > 0, f(x) = left(frac1+x2+xright)^frac1x. Let y = f(x). ln y = frac1x lnleft(frac1+x2+xright) Differentiating both sides w.r.t x: frac1y y' = -frac1x^2 lnleft(frac1+x2+xright) + frac1x cdot frac2+x1+x cdot frac1(2+x) - (1+x)1(2+x)^2 y' = y left[ -frac1x^2 lnleft(frac1+x2+xright) + frac1x(1+x)(2+x) right] ### Step 2: Apply Condition At x=1, y = f(1) = frac23. f'(1) = frac23 left[ -1 lnleft(frac23right) + frac16 right] = -frac23 lnleft(frac23right) + frac19 Also f(-1) = g(-1) = -a. Given f'(1) = f(-1) implies -a = -frac23 lnleft(frac23right) + frac19. a = frac23 lnleft(frac23right) - frac19 ### Step 3: Evaluate g(3) g(3) = 3a = 2 lnleft(frac23right) - frac13 g(3) = lnleft(frac49right) - frac13 = lnleft(frac49right) - ln(e^1/3) = lnleft(frac49e^1/3right) ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Continuity and Differentiability Class 12 Maths: Application of Derivatives

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