MA-410, Spring 2023, Homework 2, due as indicated for each problem.

All solutions must be submitted on the Moodle web site for the class at wolfware.ncsu.edu. You may upload a photo of your handwritten solution or a file of your typed solution.
Note my office hours on my schedule.


  1. Due Friday, March 3, 11:59pm
    Please prove for all positive integers M, N that GCD(2M – 1, 2N – 1) = 2GCD(M, N) – 1.
  2. Due Friday, March 3, 11:59pm
    Let the Fermat numbers be Fn= 22n + 1 for integers n ≥ 0. Please prove that 2Fn-1 ≡ 1 (mod Fn) for all n ≥ 0. [cf. ENT, §5.2, Problem 15(b), page 93.]
  3. Due Thursday, March 9, 11:59pm
    Using the Chinese Remainder Algorithm from class, which is based on interpolation by divided differences, compute an integer N such that 25 = 52 divides N, 16 = 24 divides N+1, and 27 = 33 divides N+2.
  4. Due Thursday, March 9, 11:59pm
    ENT, §5.2, Problem 13, page 93. Assume that p and q are distinct odd primes such that (p – 1) divides (q – 1). If GCD(a, pq) = 1, show that aq – 1 ≡ 1 (mod pq).
  5. Due Thursday, March 9, 11:59pm
    ENT, §5.2, Problem 19, page 93. Prove that if 6k+1, 12k+1 and 18k+1 are all prime numbers, then (6k+1)(12k+1)(18k+1) is an absolute pseudoprime. Example: 1729 = 7 times 13 times 19.