In: Advanced Math
An element a in a ring R is called nilpotent if there exists an n such that an = 0.
(a) Find a non-zero nilpotent element in M2(Z).
(b) Let R be a ring and assume a, b ∈ R have at = 0 and bm = 0 for some positive integers t and m. Find an n so that (a + b)n = 0. (You just need to find any n that will work, not the smallest!)
(c) Show that the set of nilpotent elements in a commutative ring R forms a subring of R.
(d) Does this subring from the previous question contain a unity?
(e) Are the Gaussian integers from an earlier question an integral domain? Explain your answer.