basic set theory question

by semidevil
Tags: basic, theory
semidevil is offline
Oct3-04, 08:20 PM
P: 137
ok, find the intersection of i=1 to infinitie of A(i).

A(i) = [0, to 1/i].

I dont understand what it is asking. what do they mean to find the intersection of that?

and what if A(i) = [0, 1/n)
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phoenixthoth is offline
Oct3-04, 10:01 PM
phoenixthoth's Avatar
P: 1,572
To use mathematicasque notation, Intersect[A(i), {i,1,oo}] is the set of all points in each A(i). There's only one point in all A(i)'s: 0. Therefore the intersection is {0}. Same with the second one. But if they made it (0,1/i) then it would be empty.
e(ho0n3 is offline
Oct3-04, 10:04 PM
P: 1,370
Do you mean:

[tex]\bigcap_{i=1}^{\infty} A(i)[/tex]

where A(i) = [0, 1/i]? Wouldn't the answer be {0}?

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