Suppose that $f$ is continuous at $x_0$ and $f$ satisfies $f(x)+f(y)=f(x+y)$. Then how can we prove that $f$ is continuous at $x$ for all $x$? I seems to have problem doing anything with it. Thanks in advance.

I am trying to prove that if I have $f:\mathbb{R} \to \mathbb{R}$ satisfying $\forall x,y\in\mathbb{R},f(x+y) = f(x) + f(y)$. Which is assumed continuous at $0$, that $f$ is continuous on $\mathbb{R}$ I am fairly sure it is, for that property seems to be a property of polynomials, and we know po...

I've noticed that the number of reviews required to remove a post from a queue varies. For example, to accept/reject a suggested edit, you need two votes of the same kind. If the votes are conflicting, the number goes higher. This seems to be the case for the other queues as well. (Additionally, ...