# Ideals and factor rings

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• Jul 28th 2008, 06:34 AM
Ryan0710
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.
• Jul 28th 2008, 03:47 PM
ThePerfectHacker
Quote:

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 $ra,ar\in W[N]$.