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Question: Answered & Verified by Expert
The function fx=x2-2x-3·e9x2-12x+4 is not differentiable at exactly :
MathematicsContinuity and DifferentiabilityJEE MainJEE Main 2021 (31 Aug Shift 1)
Options:
  • A Four points
  • B Two points
  • C three points
  • D one point
Solution:
1788 Upvotes Verified Answer
The correct answer is: Two points

Given thatfx=x2-2x-3e9x2-12x+4

Differentiating on both sides

f'x=x2-2x-3.e9x2-12x+4.18x-12 + x2-2x-3x2-2x-3.2x-2.e9x2-12x+4

f'(x) = x2-2x-3.e9x2-12x+4 18x-12+2x-2x2-2x-3

f'x = x2-2x-3.e9x2-12x+4.18x3-36x2-54x-12x2+24x+36+2x-2x2-2x-3

f'x = x2-2x-3.e9x2-12x+4.18x3-48x2-28x+34x-3x+1

Here f'x is not defined at x = -1 & x=3.

fx is not differentiable at two points.

 

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