If S 1 and S 2 are respectively the sets of local minimum and local maximum points of the function, f x = 9…

If S1 and S2 are respectively the sets of local minimum and local maximum points of the function, fx=9x4+12x3-36x2+25,x∈R, then
  1. S1=-2;S2={0,1}
  2. S1=-1;S2=0,2
  3.  S1=-2,0;S2={1}
  4. S1=-2,1;S2={0}

Solution

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

Asked in: JEE Main 2019 (08 Apr Shift 1)

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