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Suma
Posted:
Sun Apr 26, 2009 5:22 pm
by
andy crisan
Sa se calculeze suma
\( \sum_{k=1}^{n} k\cdot 10^{k} \)
.
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Posted:
Sun Apr 26, 2009 5:38 pm
by
Laurian Filip
Fie
\( S_n=\sum_{k=1}^n k \cdot 10^k \)
. Calculam
\( 10S_n - S_n \)
si obtinem suma.