I am going through this article, and it mentions a Kronecker made a discovery about odd prime degree polynomials that makes Abel's Theorem on the impossibility of the quintic easier to prove:
https://hubpages.com/education/Abels-Proof--A-Gentle-Introduction-to-the-Sublime-Beauty-of-Mathematics
Obviously, Kronecker has produced a lot of mathematical work, and I find it hard to find his proof on this.
https://hubpages.com/education/Abels-Proof--A-Gentle-Introduction-to-the-Sublime-Beauty-of-Mathematics
Obviously, Kronecker has produced a lot of mathematical work, and I find it hard to find his proof on this.