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# Ahhh! Maths Union Sets problem!! Grrr watch

1. Ahhh! Maths Union Sets problem!! Grrr

I'm doingf this exercise in a complementary textbook and i'm so idiotic i don't know how to do this question.
It's the last one in the chapter, maybe indicating it is difficult but i don't understand!
What is
(0,1) U {1,2} U [2,3]

Note the 3 dif. brackets... it's why i can't do this Q.

Where U = Union = Or
So the first brackets are open sets, the middle a finite and the third a closed. I don't understand how that influences, cheers!

please quote me when you erply¬!!! thanks
2. (Original post by lilpenguin)
Ahhh! Maths Union Sets problem!! Grrr

I'm doingf this exercise in a complementary textbook and i'm so idiotic i don't know how to do this question.
It's the last one in the chapter, maybe indicating it is difficult but i don't understand!
What is
(0,1) U {1,2} U [2,3]

Note the 3 dif. brackets... it's why i can't do this Q.

Where U = Union = Or
So the first brackets are open sets, the middle a finite and the third a closed. I don't understand how that influences, cheers!

please quote me when you erply¬!!! thanks
Drawing the real line and marking the unions would help with this question.

(0,1) means all the real number from 0 to 1 not including 0 and 1. But the element '1' is included in the union so (0,1) will become (0,1]

Now [2,3] means all the real number from 2 to 3 including 2 and 3. The element '2' has been added to the union but it's already contained in [2,3] so we can ignore it.

What do you end up with?

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Updated: February 1, 2010
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