# definitions of symbols used

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• Mar 9th 2009, 08:33 PM
b0mb3rz
definitions of symbols used
i am having some trouble understand what these symbols mean and how they apply to certain things

- -x Є R i know this means that x is a set of real numbers so does this mean x can be any integer
-U and the reverse U i know means union and intersection but i dont know what these 2 mean in relation to graphs etc.

thanks
• Mar 10th 2009, 01:57 PM
HallsofIvy
Quote:

Originally Posted by b0mb3rz
i am having some trouble understand what these symbols mean and how they apply to certain things

- -x Є R i know this means that x is a set of real numbers so does this mean x can be any integer

No. "R" is the set of all real numbers and x is neither "a set of real numbers" nor "any integer". x can be any real number.

Quote:

-U and the reverse U i know means union and intersection but i dont know what these 2 mean in relation to graphs etc.
I don't know what you mean by this. union and intersection apply to sets not graphs. Are you thinking of the graphs as sets of points or sets of numbers? Could you give an example?

Quote:

thanks
• Mar 11th 2009, 12:44 AM
repcvt
Quote:

Originally Posted by b0mb3rz
-u and the reverse u i know means union and intersection but i dont know what these 2 mean in relation to graphs etc.

Thanks

Attachment 10484

U depend what you definited.But must be R(= U.