# A commutative ring with unity and Ideals

1. Mar 23, 2010

### emptyboat

Let R be a commutative ring with unity. I and J are ideals of R.
Show that If I + J = R, then I∩J=IJ.

I know that IJ⊆(I∩J).
But I can't do inverse.

Last edited: Mar 23, 2010
2. Mar 23, 2010

### emptyboat

I solve it!
Thus no answer is required. :)