Exercise
What is the kernel of the morphism Z + Zi -> Z/5Z given by a + bi -> a + 2b?
(5,i)
(5)
(i - 2)
No, i -> 2 and so is not even in the kernel.
No, i - 2 is in the kernel but not in (5).
Yes.
Exercise
What is the kernel of the morphism Z + Zi -> Z/5Z given by a + bi -> a + 2b?
(5,i)
(5)
(i - 2)