Abstract Algebra | 20. The First Isomorphism Theorem

In this video we prove the first isomorphism theorem for rings and go through several examples. We then prove two more important theorems about homomorphisms, namely: 1. Ker f = {0} iff f is an injection 2. The canonical map from R to R/I is a surjective homomorphism with kernel I Small typo correction: At 13:00 it should say R[x]/(x^2)