Homework assignments for Math 28b, Spring 2003

Problem Set 1. Due Thursday, Jan. 23

  1. Page 234-237: 3,6, 12,28,40,48
  2. Show that the only units in Z[i] are 1,i,-1 and -i.
  3. Find an invertible element in Z[√7] other than 1 or -1. (That's supposed to be the square root of 7 in the brackets.)
  4. Let B consist of all matrices where a and b are real numbers. Is B a subring of M2(R)? Is B a field? Explain.