== 4. Let R be a ring with unity and has no zero divisors. If ab = 1R for a, b ER, then show that ba = 1R. (Hint: For a
Posted: Tue May 10, 2022 6:36 am
== 4. Let R be a ring with unity and has no zero divisors. If ab = 1R for a, b ER, then show that ba = 1R. (Hint: For a ring R with unity, -a = -lra.) 5. Show that all idempotent elements of an integral domain D are Op or 10. 6. There is an integral domain with n elements if and only if n is a power of a prime number.