is there a counterexample of this map isn't surjective?

44 Views Asked by At

enter image description here The ring A is a commutative ring with identity.

I think ii) is true if they are not coprime.

because for every (x+a1,....,x+an) we can find a x such that f(x)= (x+a1,....,x+an).

Could you please show me a example that f(x) is not surjective?

1

There are 1 best solutions below

3
On BEST ANSWER

Consider $A=\mathbb{Z}$ and $a_1=a_2=2\mathbb{Z}$. Then the map is not surjective. For instance the element $(\overline 1, \overline 0)$ is not in the image.