Math Help - Ideals and factor rings

1. Ideals and factor rings

Let W:R->R' be a ring homomorphism and let N be an ideal of R. show that W[N] is an ideal of ImW.

2. Originally Posted by Ryan0710
Let W:R->R' be a ring homomorphism and let N be an ideal of R. show that W[N] is an ideal of ImW.
Just do it by definition. You need to show that if $r\in W[R]$ and $a\in W[N]$ then $ra,ar\in W[N]$.