NDA2017MathematicsDefinite IntegrationActual
If f( x ) and g ( x ) are continuous functions satisfying f( x )=f( a - x ) and g ( x )+ g ( a - x )=2 , then what is ₀^ a f( x ) g ( x ) dx equal to?
Options
- A₀^a g(x) d x
- B₀^ a f( x ) dx
- C2 ₀^ a f( x ) dx
- D0
Correct answer
B. ₀^ a f( x ) dx
Step-by-step solution
aligned & I= ₀^a f(x) g(x) d x & I= ₀^a f(a-x) g(a-x) d x & I= ₀^a f(x) [2-g(x)] d x & f(a-x)=f(x) and g(a-x)=2 g(x) & I= ₀^a 2 f(x) d x- ₀^a f(x) g(x) d x & I=2 ₀^a f(x) -I & 2 I=2 ₀^a f(x) d x 2 & I= ₀^a f(x) d x & a a f(x)= ₀^a f(a-x) d x & ( Given f(x)=f(x)) aligned