I have always wondered this and apologize if I'm reposting, but I don't know how to find out the answer, also Im a little new to math but always liked it, and I'm learning and am starting out with complex analysis, so here goes. I believe:
$i={\sqrt {-1}} = {\sqrt {\frac{1}{-1}}} = {{\frac{\sqrt {1}}{\sqrt {-1}}}}=\frac{1}{i}$
But that gives you $i^2=1$ and not $-1$. Where did I go wrong?