Which of the following is an example of why irrational numbers are not closed under addition?
√4+√4=2+2=4,
and 4 is not irrational
1/2+1/2=1, and 1 is not irrational
√10+(-√10) = 0, and 0 is not irrational
-3 +3 = 0, and 0 is not irrational