Is At Least One of a or b Even in the Pythagorean Theorem?

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Homework Help Overview

The discussion revolves around the properties of integers in the context of the Pythagorean theorem, specifically examining the statement that if \( a \), \( b \), and \( c \) are integers such that \( a^2 + b^2 = c^2 \), then at least one of \( a \) or \( b \) must be even.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the implications of the statement regarding the parity of \( a \) and \( b \), questioning whether both can be odd and discussing the conditions under which the original statement holds true.

Discussion Status

Participants are actively engaging with the logical structure of the statement, with some attempting to clarify the contradiction by analyzing the conditions under which \( a \) and \( b \) can be odd or even. There is a focus on understanding the implications of the definitions and the logical opposites of the statements involved.

Contextual Notes

Some participants express uncertainty about the correctness of their interpretations and the implications of their assumptions regarding the parity of \( a \) and \( b \). The discussion includes references to modular arithmetic as a potential tool for analysis.

Instinctlol
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Homework Statement


If a,b and c are integers and a2+b2=c2, then at least one of a and b is even.


2. Contradiction statement
There exist an integer a,b,c such that a2+b2=c2 and a or b is odd



The Attempt at a Solution


I am not sure if my contradiction statement is correct because of this part, then at least one of a and b is even. I think it means 1 has to be even and the other could be even or odd. Let me know if my contradiction is right or wrong and point me in the right direction to start.
 
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The statement "at least one of a and b is even" is true if either a or b is even, or if both a and b are even. The opposite of this statement is "neither a nor b is even."
 
So either a or b is odd would be correct?
 
Suppose a=1 and b=2. Then the statement "either a or b is odd" is true because a is odd. The statement "at least one of a and b is even" is true because b is even. So "either a or b is odd" can't be the opposite of "at least one of a and b is even."
 
Instinctlol said:
So either a or b is odd would be correct?
If you'll read more closely, you'll see that I said neither a nor b is odd.
 
Mark44 said:
If you'll read more closely, you'll see that I said neither a nor b is odd.

I reread your statement and it says both a and b are not even so they both must be odd?
 
Instinctlol said:
I reread your statement and it says both a and b are not even so they both must be odd?

Yes, to prove the contradiction you would assume they are both odd. Think about mod 4.
 
Last edited:

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