By taking the laplace transform and using the convolution

Question

Let f be a piecewise continuous function on [0,T]. Define f on the whole of [0,inf) by f(t+nT) for all t and all integer n. Show that the Laplace transform if f is given by

L[f(t)] = 1/[1-exp(-sT)]*int(exp(-st)*f(t)dt,t=0..T)

By taking the Laplace transform and using the convolution theorem, obtain the solution of the integral equation

f(t) = 1+t+int[(t-u)f(u)du,u=0..t)