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Question: Answered & Verified by Expert
If S1 and S2 are respectively the sets of local minimum and local maximum points of the function, fx=9x4+12x3-36x2+25,xR, then
MathematicsApplication of DerivativesJEE MainJEE Main 2019 (08 Apr Shift 1)
Options:
  • A S1=-2;S2={0,1}
  • B S1=-1;S2=0,2
  • C  S1=-2,0;S2={1}
  • D S1=-2,1;S2={0}
Solution:
2734 Upvotes Verified Answer
The correct answer is: S1=-2,1;S2={0}

y=9x4+12x3-36x2+25

Differentiating,

dydx=36x3+36x2-72x
       =36xx2+x-2

       =36xx+2x-1

Sign convention for dydx

S1=-2,1 & S2=0

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