f(x) = cosx - ∫(x - t)f(t) dt ; t ∈ [0, x] , then f''(x) + f'(x) is equal to

Question

\(f(x) = cos x - \int\limits_0^x (x-t) f(t)dt\), then f''(x) + f'(x) is equal to

a. – cosx

b. – sinx 

c. 0

d. none of these

Answer 1

Correct option is a. – cosx