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JEE Main202131 Aug 2021Morning ShiftMathematicsContinuity and DifferentiabilityActual

The function f x = x 2 - 2 x - 3 · e 9 x 2 - 12 x + 4 is not differentiable at exactly :

Options

  1. AFour points
  2. BTwo points
  3. Cthree points
  4. Done point

Correct answer

B. Two points

Step-by-step solution

Given that f x = x 2 - 2 x - 3 e 9 x 2 - 12 x + 4 Differentiating on both sides f ' x = x 2 - 2 x - 3 . e 9 x 2 - 12 x + 4 . 18 x - 12   +   x 2 - 2 x - 3 x 2 - 2 x - 3 . 2 x - 2 . e 9 x 2 - 12 x + 4 ⇒ f ' ( x )   =   x 2 - 2 x - 3 . e 9 x 2 - 12 x + 4   18 x - 12 + 2 x - 2 x 2 - 2 x - 3 ⇒ f ' x   =   x 2 - 2 x - 3 . e 9 x 2 - 12 x + 4 . 18 x 3 - 36 x 2 - 54 x - 12 x 2 + 24 x + 36 + 2 x - 2 x 2 - 2 x - 3 ⇒ f ' x   =   x 2 - 2 x - 3 . e 9 x 2 - 12 x + 4

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