Proving the Existence of One Positive Integer m and n for x in Real Numbers

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In summary, to prove that there will always be one and only one positive integer m such that m=< x <m+1 and one and only one positive integer n such that n< x =< n+1, you can consider two sets X and Y, where X={k belongs to Z : k<x} and Y={k belongs to Z : k<=x}. By setting m=supX and n=supY, you can prove that m belongs to X and n belongs to Y, thus proving the existence of one and only one positive integer between x and x+1.
  • #1
YourLooks
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x is a real number, could you tell me how to prove that there will always be one and only one positive integer m such that m=< x <m+1 and one and only one positive integer n such that n< x =< n+1 ?
Thank you...
 
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  • #2
Looks like homework, read the rules on homework above (we'll help you, but we won't do it for you).
 
  • #3
Oh, Poet jcsd, I didn't know that.
But how will Poet help me ?
 
  • #4
YourLooks said:
x is a real number, could you tell me how to prove that there will always be one and only one positive integer m such that m=< x <m+1 and one and only one positive integer n such that n< x =< n+1 ?
Thank you...
Suppose there are 2 sets X and Y, X={k belongs to Z : k<x}, Y={k belongs to Z : k<=x}, which means X and Y are not set zero and there should be a sup. Now you only need to let m=supX and n=supY then try to prove m belongs to X and n belongs to Y. Thats all.
 
  • #5
Thank you for helping Yourlooks, you are really new to this forum :wink:
 

1. How can one prove the existence of positive integers m and n for any real number x?

The existence of positive integers m and n for any real number x can be proven using the Well-Ordering Principle, which states that every non-empty set of positive integers has a least element. This means that for any real number x, there exists a positive integer m such that x < m, and there exists a positive integer n such that x > -n.

2. Can you provide an example of a proof for the existence of positive integers m and n for a specific real number x?

Yes, for example, let x = 5. We can choose m = 6 and n = 4, since 5 < 6 and 5 > -4. Therefore, we have proven the existence of positive integers m and n for x = 5.

3. Is there a specific method or algorithm for proving the existence of positive integers m and n for any real number x?

Yes, the Well-Ordering Principle is a commonly used method for proving the existence of positive integers m and n for any real number x. Other methods may also be used, depending on the specific problem at hand.

4. Can the existence of positive integers m and n for a real number x be proven without using the Well-Ordering Principle?

Yes, it is possible to prove the existence of positive integers m and n for a real number x using other mathematical principles, such as the Archimedean property or the completeness property of real numbers. However, the Well-Ordering Principle is often the simplest and most straightforward method for proving such existence.

5. Why is it important to prove the existence of positive integers m and n for a real number x?

Proving the existence of positive integers m and n for a real number x is important because it allows us to establish the mathematical properties and relationships between real numbers and positive integers. This is essential in many mathematical fields and applications, such as algebra, calculus, and number theory.

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