opticaltempest
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Homework Statement
I want to show that if C and D and closed sets, then C \bigcup D is a closed set.
Homework Equations
A set is called closed iff the set contains all of its accumulation points.
The Attempt at a Solution
In order for me to prove this statement, I will be able to use the fact that C and D are closed sets. Can I prove this statement by supposing that if c is an accumulation point of C and d is an accumulation point of D, then both c and d will be accumulation points of C \bigcup D ?