# Math Help - Ideals of Rings

1. ## Ideals of Rings

let R be a commutative ring and fix a in R. Show that I_a = {x in R | ax=0} is an ideal of R.

2. Hi
Do you know the definition of an ideal? Which part can't you prove (additive subgroup, closed under multiplication) ?
Don't forget $R$ commutativity.