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Union and Intersection of sets

  • Thread starter Goldenwind
  • Start date
  • #1
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Homework Statement


a) Find: [tex]\bigcup_{i=1}^{\infty}} A_i[/tex]


b) Find: [tex]\bigcap_{i=1}^{\infty}} A_i[/tex]

Where [itex]A_i[/itex] = (0,i), that is, the set of real numbers x with 0 < x < i

I was doing okay when they gave me [itex]A_i[/itex] = {i, i+1, i+2, ...}, but now that they're giving me (0,i), and introducing x, I'm getting confused.
 

Answers and Replies

  • #2
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Just noticed that I placed this in the wrong forum. I usually come to the Physics forum, however this time I meant for Calculus.
Tried to find a way to delete or move it, but not finding a way.

If an admin finds this, just delete it. I'll post it in the proper forum.

Apologies.
 
  • #3
CompuChip
Science Advisor
Homework Helper
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Try making a picture. Draw a long line, this is the set of all real numbers. We indicate an open interval (a, b) by putting a bracket ( at the point a, and a bracket ) at the point b. Also see this webpage.
Now draw some intervals (0, 1), (0, 2), (0, 4) and look at their intersection and their union. Post a conjecture about the answer, we'll help you prove it.
 

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