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@NicolasT
Created December 6, 2009 22:08
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Stel s = 1 + 2 + 3 + 4 + 5 + ...
-3s = (1 - 4)s
= (1 + 2 + 3 + 4 + 5 + ...) - 2(2 + 4 + 6 + 8 + 10 + ...)
= 1 - 2 + 3 - 4 + 5 - ... [*1]
= 1 - (2 - 3 + 4 - 5 + ...)
= 1 - (1 - 2 + 3 - 4 + 5 - ...) - (1 - 1 + 1 - 1 + ...)
Lemma:
stel t = 1 - 1 + 1 - 1 + 1 - ...
1 - t = 1 - (1 - 1 + 1 - 1 + 1 - ...)
= 1 - 1 + 1 - 1 + 1 - ...
= t
=> t = 1 / 2 [*2]
(vervolg)
= 1 - (1 - 2 + 3 - 4 + 5 - ...) - (1 / 2) [wegens *2]
= 1 + 3s - (1 / 2) [wegens *1]
=> -6s = 1 - (1 / 2)
=> s = -1 / 12
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