Is E a subset of ]0,2] and how does it relate to ]0,2]?

AI Thread Summary
The discussion revolves around proving whether the set E, defined as E = {(a+b)/ab : a, b ∈ N*}, is a subset of the interval ]0,2]. Participants clarify the notation and seek to establish that every element x in ]0,2] can be expressed in the form (a+b)/ab for some positive integers a and b. There is a focus on demonstrating that rational numbers within this interval can be represented by the formula provided. The conversation also touches on the inclusion of irrational numbers, such as √2, in the interval and its implications for the subset relationship. Ultimately, the goal is to confirm the relationship between E and the interval ]0,2].
Andrax
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we have E=(a+b)/ab (a,b)EN*
1/ prove that E C ]0,2] (i already duid that )
2/ is ]0,2] E E? shelp me in this one!


Homework Equations





The Attempt at a Solution


x \in ]0,2] \Rightarrow x \in E
 
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Andrax said:
we have E=(a+b)/ab (a,b)EN*
1/ prove that E C ]0,2] (i already duid that )
2/ is ]0,2] E E? shelp me in this one!


Homework Equations





The Attempt at a Solution


x \in ]0,2] \Rightarrow x \in E

If E=(a+b)/ab what does EN* mean? What does ]0,2]E E mean? Please state your problem with proper notation.
 
LCKurtz said:
If E=(a+b)/ab what does EN* mean?
E means ##\in## and N* means the positive integers, I believe.
LCKurtz said:
What does ]0,2]E E mean? Please state your problem with proper notation.
I second that.
 
well sorry didn't find the proper notations in the advanced mode umm any solution?
 
Andrax said:
well sorry didn't find the proper notations in the advanced mode umm any solution?

You can use ε in the top row of Quick Symbols (on the right after you click Go Advanced). Or you can use LaTeX: [ itex ] \in [ /itex ] (without the spaces).

Also, tell us what you meant by N*.
 
Andrax said:
well sorry didn't find the proper notations in the advanced mode umm any solution?

You could try using words:
E = {(a+b)/(ab): a,b positive integers}. And "is ]0,2] a subset of E?"
or
E = {(a+b)/(ab): a,b,in N*}, and "is ]0,2] subset E?"

RGV
 
Ray Vickson said:
You could try using words:
E = {(a+b)/(ab): a,b positive integers}. And "is ]0,2] a subset of E?"
or
E = {(a+b)/(ab): a,b,in N*}, and "is ]0,2] subset E?"

RGV

I want to prove that ]0,2 is a subset of E E = {(a+b)/(ab): a,b,in N*}, and "is ]0,2] subset E?"
 
Aren't all the numbers in E rational?
 
Andrax said:
I want to prove that ]0,2 is a subset of E E = {(a+b)/(ab): a,b,in N*}, and "is ]0,2] subset E?"
In other words, you want to show that if 0< x\le 2, the x= (a+ b)/(ab) for some positive integers a and b. \sqrt{2} lies between 0 and 2 doesn't it?
 
  • #10
HallsofIvy said:
In other words, you want to show that if 0< x\le 2, the x= (a+ b)/(ab) for some positive integers a and b. \sqrt{2} lies between 0 and 2 doesn't it?

yes it does what's your point?
 
  • #11
ohh i get your point wow that's really easy don't know how i missed it
 
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