Manipal MET2012MathematicsDifferentiation
Let f be twice differentiable function satisfying f(1)=1, f(2)=4, f(3)=9 , then
Options
- Af^ (x)=2, x R
- Bf^ (x)=5=f^ (x) . For some x (1,3)
- Cthere exists atleast one x (1,3) such that f^ (x)=2
- DNone of the above
Correct answer
C. there exists atleast one x (1,3) such that f^ (x)=2
Step-by-step solution
Let g(x)=f(x)-x^2 g(x) has atleast 3 real roots which are x=1,2,3 (by mean value theorem) g^ (x) has atleast 2 real roots in x (1,3) g^ (x) has atleast 1 real root in x (1,3) f^ (x)=2 for atleast one x (1,3)