For one part of a problem I am working on, I am trying to show that $y'(t) \geq 1$ for all $t \geq 0$ when $y'= 1- \int^t_0 g(s)y(s) ds$
When $g(t)$ is periodic, $g(t) <0$ for all $t$, and $y(0)=y'(0)=1$.
So, obviously I have to show that the integral is $\leq 0$, but I am having some trouble remembering any rules of integrating with periodic functions that would be helpful.
