BITSAT2011MathematicsApplication of DerivativesActual
The function ( f ( x )=2 x ^3-3 x ^2-12 x +4 ), has
Options
- Atwo points of local maximum
- Btwo points of local minimum
- Cone maxima and one minima
- Dnomaxima or minima
Correct answer
C. one maxima and one minima
Step-by-step solution
( aligned & f(x)=2 x^3-3 x^2-12 x+4 & f^ (x)=6 x^2-6 x-12=6 (x^2-x-2 ) & =6(x-2)(x+1) aligned ) For maxima and minima ( f ^ ( x )=0 ) ( 6( x -2)( x +1)=0 x =2,-1 ) Now, ( f ^ ( x )=12 x -6 ) ( aligned & At x =2 ; f ^ ( x )=24-6=18 > 0 & x =2, local min. point & At x =-1 ; f ^ ( x )=12(-1)-6=-18 < 0 & x =-1 local max. point aligned )