Proving x=y using field axioms in R | Field Axiom Proof

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Homework Help Overview

The discussion revolves around proving that if \( x, y \in \mathbb{R} \) and \( x = y \), then \( wx = wy \) using only field axioms. Participants are exploring the implications of equality and the properties of real numbers under multiplication.

Discussion Character

  • Conceptual clarification, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Some participants suggest that the proof can be straightforwardly derived using field axioms, while others express concern about the simplicity of the problem. There are discussions about the necessity of assuming \( w \neq 0 \) and the implications of equality in the context of field axioms.

Discussion Status

The discussion is active, with participants sharing their thoughts on the proof's validity and the assumptions required. Some guidance has been offered regarding the conditions under which the statement holds, but there is no explicit consensus on the necessity of additional axioms for equality.

Contextual Notes

Participants note that the problem may require specific conditions on \( w \) and question whether the field axioms alone are sufficient for the proof. There is also mention of the role of mathematical logic in understanding equality.

Tomp
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Homework Statement



Using only the fi eld axioms, prove that if x,y ε R and x = y then wx = wy.

Homework Equations



http://mathworld.wolfram.com/FieldAxioms.html

The Attempt at a Solution



The solution to this can be solved within 2 lines or so using the field axiom inverses/multiplications ,however, this is one of a couple of assignment questions and it seems a little too easy? Am I thinking about this question correctly?
 
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It's a very easy problem - there is no "trick" to it. I just did this quickly to check it; I got it using distributivity and additive inverses.
 
Tomp said:

Homework Statement



Using only the fi eld axioms, prove that if x,y ε R and x = y then wx = wy.

Homework Equations



http://mathworld.wolfram.com/FieldAxioms.html

The Attempt at a Solution



The solution to this can be solved within 2 lines or so using the field axiom inverses/multiplications ,however, this is one of a couple of assignment questions and it seems a little too easy? Am I thinking about this question correctly?

Notice :

x = y ⇔ x - y = 0

So similarly :

wx = wy
wx - wy = 0
w(x-y) = 0
w0 = 0

So either w=0 or 0=0. I am pretty sure your question should require that w≠0 and then the rest should be obvious.
 
Zondrina said:
Im pretty sure your question should require that w≠0 and then the rest should be obvious.

Why should you require w≠0? It's still a true statement if you take any w real.
 
Zondrina said:
Notice :

x = y ⇔ x - y = 0

So similarly :

wx = wy
NO![/size]
The equation above is what the OP needs to show. You can't start off by assuming what you're trying to prove.
Zondrina said:
wx - wy = 0
w(x-y) = 0
w0 = 0

So either w=0 or 0=0. I am pretty sure your question should require that w≠0 and then the rest should be obvious.
 
I don't think it can be proven from the field axioms. Rather, you need axioms for the equality operator. This is usually handled in logic courses.

For now, I think it is enough to say that: x and y are the same number, so wx and wy must be the same number as well.

For a more rigorous approach, you need mathematical logic.
 

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