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Ruxy01
a fost răspuns

Calculati suma permutarii
n
(epsilon)∑ k!*k
k=1

Răspuns :

[tex]\displaystyle\sum_{k=1}^nk!\cdot k=\displaystyle\sum_{k=1}^nk!(k+1-1)=\displaystyle\sum_{k=1}^n (k!\cdot (k+1)-k!)=\\ =\displaystyle\sum_{k=1}^n ((k+1)!-k!)=2!-1+3!-2!+\ldots +(n+1)!-n!=\\ =\boxed{(n+1)!-1} [/tex]

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