BITSAT2012MathematicsApplication of DerivativesActual
If f ( x )= a ²-1 a ²+1 x ³-3 x +5 is a decreasing function of x in R , then the set of possible values of a (independent of x ) is
Options
- A(1, )
- B(- ,-1)
- C[-1,1]
- DNone of these
Correct answer
C. [-1,1]
Step-by-step solution
f^ (x)=3 ( a²-1 a²+1 ) x²-3 f ^ ( x )<0 for all x if a ²-1 0 -1 a 1