Math Problem Statement

Disprove the following statement by giving a counterexample. For every integer p, if p is prime then p2 − 1 is even. Counterexample: Consider the ordered pair (p, p2 − 1) =

Solution

We are tasked with disproving the statement:

"For every integer pp, if pp is prime, then p21p^2 - 1 is even."

Counterexample:

Consider the prime number p=2p = 2.

  1. p2=22=4p^2 = 2^2 = 4
  2. p21=41=3p^2 - 1 = 4 - 1 = 3

Here, 33 is an odd number, which contradicts the claim that p21p^2 - 1 is even for all primes pp.

Thus, the statement is false. A counterexample is the ordered pair (2,3)(2, 3), where p=2p = 2 and p21=3p^2 - 1 = 3, which is odd.

Would you like more details on this or have any questions?

Here are 5 follow-up questions to further explore related concepts:

  1. What are the conditions for a number to be considered prime?
  2. Can you generalize a statement about when p21p^2 - 1 is even?
  3. How does the parity (odd/even nature) of numbers change after squaring?
  4. What other small primes might provide insight into this problem?
  5. Is p21p^2 - 1 always odd for certain types of primes?

Tip: When analyzing patterns involving primes, remember that 2 is the only even prime number, which often leads to unique cases.

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Math Problem Analysis

Mathematical Concepts

Prime Numbers
Parity (Odd/Even Numbers)
Counterexamples

Formulas

p^2 - 1

Theorems

Definition of Prime Numbers
Parity Theorem (Even/Odd nature of numbers)

Suitable Grade Level

Grades 8-10