Let f(X) be a polynomial of degree n with complex coefficients, and let
f(X)1=j=1∑qh=1∑nj(X−rj)hλjh
be the decomposition of the rational fraction 1/f(X) into simple elements (Alg., VII. 7, n 2). Show that, for any regulated function b, the function
t↦j=1∑qh=1∑njλjh∫t0t(h−1)!(t−s)h−1elj(t−s)b(s)ds
is an integral of the equation f(D)x=b(t).