Răspunsuri

2014-11-09T12:13:11+02:00
Cel mai inteligent răspuns!
2014-11-09T12:19:40+02:00
2+4+6+...+2n=2·(1+2+3+...+n)=2· \frac{n(n+1)}{2} =n·(n+1)=n²+n
atat se poate calcula
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