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| − | <math>\sum_{n = M}^N \alpha^n = \alpha^M - \alpha^{N-1}</math> | + | <math>\sum_{n = M}^N \alpha^n = \alpha^M - \alpha^{N-1} / (1 - \alpha)</math> |
Revision as of 02:42, 20 July 2009
$ \sum_{n = M}^N \alpha^n = \alpha^M - \alpha^{N-1} / (1 - \alpha) $
