How to prove that set A is Lebeg measurable?

Question

I'm wondering how to solve this. We have an infinite countable set A ⊂ R is such that λ * (A) =0, . I would appreciate any help. Thanks.

And by the way, all countable sets have outer measure $0$ in Euclidean space. — Rushabh Mehta, Mar 03 '21 at 17:19
Welcome to Mathematics Stack Exchange. Lebesgue (pronounced like Lebeg) was a French mathematician — J. W. Tanner, Mar 03 '21 at 17:36

score -2 · Answer 1 · answered Mar 03 '21 at 17:23

-2

Any countable set is measurable since it is a countable union of singletons, which are measurable.

answered Mar 03 '21 at 17:23

nullUser

1 Answers1