Lie groups and Lie algebras: Invariant theory (optional extra video)
Channel: Jonathan Evans
Date: 2021-09-08

We discuss in detail how to view the space of binary quadratic forms as a representation of SL(2,C) and why b^2 - 4ac is an invariant. This relies on the earlier video http://jde27.uk/lgla/28_plethysm.html and corrects a mistake in an earlier version of that video.