using the definition: . f(x)=x if x is an integer. f(x)=0 if x is not an integer. Prove that f is not continuous at=3 so we use the negation of the above definition. how do we know Is there a general method? Thanks
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Let . Then for all , . In this case, its probably easier to look at the one-sided limits at an integer: since f is 0 as you approach an integer, the limit of f at any integer is 0, but f is not zero there, so it is discontinuous.
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