a)$ |h(x)| \leq (\int |f(x-y)|^p dy)^(1/p)(\int |g(y)|^q dy)^(1/q) = (\int |f(z)|^p dz)^(1/p)(\int |g(y)|^q dy)^(1/q) \leq ||f||_{p}||g||_{q} $
