Problem 4: Disprove the following statements.
(a) Suppose a ∈ Z and n,m ∈ N. Then a^na^m=a^nm.
(b) For any integer n≥0,n^2−n+ 41 is prime.


Problem 4: Disprove the following statements. (a) Suppose a ∈ Z and n,m ∈ N. Then...
1. [10 marks] Modular Arithmetic. The Quotient-Remainder theorem states that given any integer n and a positive integer d there exist unique integers q and r such that n = dq + r and 0 r< d. We define the mod function as follows: (, r r>n = qd+r^0<r< d) Vn,d E Z d0 Z n mod d That is, n mod d is the remainder of n after division by d (a) Translate the following statement into predicate logic:...
3. Prove the statements that are true and give counterexamples to disprove those that are false. (a). Va,b,n E Z* , if a’ =b}(modn) then a =b(modn). (8 points) (b). If p> 2 and q> 2 are prime, then p? +q must be composite. (12 points)
4. (15 points) Prove or disprove each one of the following statements: ·0(f(n) + g(n)) = f(n) + 0(g(n))I f(n) and g(n) are strictly positive for all n ·0(f(n) × g(n)) positive for all n f(n) 0(g(n))I f(n) and g(n) are strictly
Problem (2), 10 points Disprove the following statement: If m > 2 is an integer, then (a + b) (mod m) = a (mod m) +b (mod m) for all integers a and b.
13. (i) For each of the following equations, find all the natural numbers n that satisfy it (a) φ(n)-4 (b) o(n) 6 (c) ф(n) 8 (d) φ(n) = 10 (ii) Prove or disprove: (a) For every natural number k, there are only finitely many natural num- bers n such that ф(n)-k (b) For every integer n > 2, there are at least two distinction integers that are invertible modulo n (c) For every integers a, b,n with n > 1...
For Exercises 1-15, prove or disprove the given
statement.
1. The product of any three consecutive integers is even.
2. The sum of any three consecutive integers is
even.
3. The product of an integer and its square is
even.
4. The sum of an integer and its cube is even.
5. Any positive integer can be written as the sum of
the squares of two integers.
6. For a positive integer
7. For every prime number n, n +...
Discrete Math
□ Prove or disprove: If n is any odd integer then (-1)"--1 Problem 6:
Problem 6.13 Disprove the following statement by finding a counterexample: ∀x, y, z ∈ R, if x > y then xz > yz. Problem 6.14 Disprove the following statement by finding a counterexample: ∀x ∈ R, if x > 0 then, 1 /( x+2) = (1/ x) + (1/2)
(4) Suppose that an → a. Prove or disprove: (a) If an is an upper bound fora set S for all n, then a is also an upper bound for S. (b) If an € (0,1) for all n, then a € (0,1). (c) If an € [0,1] for all n, then a € [0, 1]. (d) If an is rational, then a is rational.
(a) Let n be any positive integer. Briefly explain (no formal proofs) why n > 1 ≡ ¬(n = 1). (b) Recall that a positive integer p is prime iff there do not exist a positive integers n and m, both greater than 1, such that p = nm. (I.e., Prime(p) means ¬∃n ∃m (n > 1 ∧ m > 1 ∧ p = nm).) Give a formal proof of the following: for any prime p, any positive integers n...