Determine the groups of quadratic residues Qn for all n in the range 10 ≤ n ≤ 20.

31. Prove statement of Theorem : for all integers and .

Find all monic irreducible polynomials of degree 2 over Z3.

6. For each of the following values of , describe all the abelian groups of order , up to isomorphism. b. c. d. e. f.