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Why is the following statement on sequence convergence false?

I can't see why

"If 0 ≤ an ≤ bn for n ≥ 1 and {bn} converges, then {an} converges." is false.

1 Answer

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  • kb
    Lv 7
    10 years ago
    Favorite Answer

    Let an = 2 + (-1)^n, while bn = 3 for n = 1, 2, ... .

    That is, {an} = {1, 2, 1, 2, 1, 2, ...} and {bn} = {3, 3, 3, 3, 3, 3, ...}

    Note that {bn} converges to 3, while {an} diverges because it has no unique limit.

    (The even terms of an converge to 2, while the odd terms of an converge to 1.)

    I hope this helps!

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