Yeah, I think you're thinking of a Bring radical: https://en.wikipedia.org/wiki/Bring_radical https://en.wikipedia.org/wiki/Bring_radical Edit: Oh, but that on

Yeah, I think you're thinking of a Bring radical: https://en.wikipedia.org/wiki/Bring_radical https://en.wikipedia.org/wiki/Bring_radical Edit: Oh, but that only lets you solve some quintics. https://news.ycombinator.com/item?id=14686886 https://news.ycombinator.com/item?id=14686886 describes the functions you need to solve all quintics.