JEE Advanced2006MathematicsDifferentiationActual
If f^ (x)=-f(x) , where f(x) is a continuous double differentiable function and g(x)=f^ (x) . If F(x)= (f ( x 2 ) )^2+ (g ( x 2 ) )^2 and F(5)=5 , then F(10) is
Options
- A0
- B5
- C10
- D25
Correct answer
B. 5
Step-by-step solution
As, f(x)=-f(x) d d x (f^ (x) )=-f(x) g^ (x)=-f(x) and f^ (x)=g(x) where, F^ (x)=2 (f ( x 2 ) ) f^ ( x 2 ) 1 2 +2 (g ( x 2 ) ) g^ ( x 2 ) 1 2 =0 [using Eq. (1)] F(x) is constant F(10)=F(5)=5