Is Commutativity of Addition True for Integers?

  • Thread starter iwonde
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I was just thinking that the equations were incorrect and if corrected, would make the rest of his proof moot. I was trying to get him to clarify what the equations were supposed to be.So, I think you're probably right. I'll wait to see what the opening poster says.In summary, the conversation discusses the proof that for any two integers a and b, a+b=b+a. It is mentioned that this holds for natural numbers and the attempt at a solution involves using the definition of ordered pairs and the commutativity of addition. However, there is a question about the validity of the equations used in the solution.
  • #1
iwonde
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Homework Statement


Prove that for any two integers a and b, a+b=b+a. You may use the face that this holds for natural numbers.


Homework Equations





The Attempt at a Solution


a=(x,y), b=(u,v)
x,y,u,v are natural numbers
a+b = (x,y)+(u,v) = (u,v)+ (x,y) = b+a

I'm not sure if my attempt was correct.
 
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  • #2
iwonde said:
(x,y)+(u,v) = (u,v)+ (x,y)

This step assumes the conclusion. You have to prove it.

Hint: What is the definition of (x,y)+(u,v)?
 
  • #3
iwonde said:

Homework Statement


Prove that for any two integers a and b, a+b=b+a. You may use the face that this holds for natural numbers.


Homework Equations





The Attempt at a Solution


a=(x,y), b=(u,v)
What do the equations above mean? a and b are integers, not ordered pairs.
iwonde said:
x,y,u,v are natural numbers
a+b = (x,y)+(u,v) = (u,v)+ (x,y) = b+a

I'm not sure if my attempt was correct.
 
  • #4
Mark44 said:
What do the equations above mean? a and b are integers, not ordered pairs.
I suspect the opening poster forgot to tell us that he's working with a specific presentation of the integers -- represented as the set of ordered pairs of natural numbers modulo an equivalence relation -- along with the definition of + that he's using.

(Of course, maybe that's exactly what you were prompting the opening poster to say -- if so, sorry 'bout that)
 
  • #5
Nope, I wasn't thinking that at all, so no problem.
 

1. What is the definition of commutativity in mathematics?

Commutativity is a property in mathematics that states that the order of operands in a mathematical operation does not affect the result. In other words, the order can be switched without changing the outcome.

2. How do you prove that a+b=b+a for integers?

To prove that a+b=b+a for integers, we can use the commutativity property of addition, which states that the sum of two numbers is the same regardless of the order in which they are added. Therefore, if we switch the order of a and b in the equation a+b=b+a, we will still get the same result.

3. Can the property of commutativity be applied to all mathematical operations?

Yes, the property of commutativity can be applied to all mathematical operations, including addition, subtraction, multiplication, and division. However, it is important to note that it may not hold true for all types of numbers, such as matrices or complex numbers.

4. What is the significance of proving a+b=b+a for integers?

The significance of proving a+b=b+a for integers is that it shows that the commutativity property holds true for integers. This means that the order of numbers does not matter when performing addition with integers, which can make solving equations and simplifying expressions easier.

5. Can the property of commutativity be extended to more than two numbers?

Yes, the property of commutativity can be extended to any number of operands. This means that the order of any number of numbers can be changed without affecting the result of the operation. For example, if we have the numbers a, b, and c, the commutativity property would state that a+b+c = a+c+b = b+a+c = b+c+a = c+a+b = c+b+a.

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