- #1

- 117

- 0

So this is what I have so far:

Let [itex]\{A_{i\in I}\}[/itex] be a collection of open sets in [itex]\mathbb{R}[/itex]. I want to show that [itex]\bigcup_{i\in I}A_{i}[/itex] is also open...

Any ideas from here?

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- #1

- 117

- 0

So this is what I have so far:

Let [itex]\{A_{i\in I}\}[/itex] be a collection of open sets in [itex]\mathbb{R}[/itex]. I want to show that [itex]\bigcup_{i\in I}A_{i}[/itex] is also open...

Any ideas from here?

- #2

Science Advisor

Gold Member

MHB

- 2,725

- 6

what is your definition of open set?

- #3

- 117

- 0

- #4

Science Advisor

Gold Member

MHB

- 2,725

- 6

can you continue...?

- #5

- 117

- 0

Am I on the right track?

- #6

Science Advisor

Gold Member

MHB

- 2,725

- 6

looks good to me.

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