- #1
robertdeniro
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Homework Statement
X and Y are two closed non-empty subsets of R (real numbers).
define X+Y to be (x+y | x belongs to X and y belongs to Y)
give an example where X+Y is not closed
Homework Equations
The Attempt at a Solution
i tried X=all integers and Y=[0 1] but that didnt work out.
i know X+Y must be non-finite because all finite subsets are closed.