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Question: Answered & Verified by Expert
If x=1 is a critical point of the function f(x)=3x2+ax-2-aex, then 
MathematicsApplication of DerivativesJEE MainJEE Main 2020 (05 Sep Shift 2)
Options:
  • A x=1 and x=-23 are local minima of f
  • B x=1 andx=-23 is a local maxima of f
  • C x=1 is a local maxima andx=-22 is a local minima of f
  • D x=1 is a local minima andx=-23 are local maxima of f
Solution:
2656 Upvotes Verified Answer
The correct answer is: x=1 is a local minima andx=-23 are local maxima of f

f(x)=3x2+ax-2-aex
f'(x)=3x2+ax-2-aex+ex(6x+a)=ex3x2+(a+6)x-2

  x=1 is a critical point     f'(1)=0

3+a+6-2=0
a=-7

f'(x)=ex3x2-x-2=ex3x2-3x+2x-2=ex(3x+2)(x-1)

maxima at x=-2 3 minima at x=1

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