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I am currently focused on Chapter 3: Sets with Two Binary Operations: Rings ... ...

I need help with Bland's proof of the Second Isomorphism Theorem for rings ...

Bland's Second Isomorphism Theorem for rings and its proof read as follows:

View attachment 7969

https://www.physicsforums.com/attachments/7970

In the above proof by Bland we read the following:

" ... ... This map is easily shown to be a well defined ring homomorphism with kernel \(\displaystyle I_1/I_2\). ... ... "I can see that \(\displaystyle f\) is a ring homomorphism ... but how do we prove that the kernel is \(\displaystyle I_1/I_2\) ... ... ?Hope someone can help ...

Peter