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.

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?-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