Nowadays we can easily prove the following fact using polynomial long division:
If $a$ is a root of the polynomial $f$, then there exists a polynomial $g$ such that $f(x) = (x - a)g(x)$.
I can't imagine how to prove this without polynomial long division. I have two questions:
- Who invented polynomial long division, and when?
- Was the above theorem known before the discovery of polynomial long division? If so, how was it proven?