Răspunsuri

2014-08-13T18:48:00+03:00
A) \frac{^{n+1)}1}{n}- \frac{^{n)}1}{n+1}  = \frac{n+1}{n(n+1)} - \frac{n}{n(n+1)} = \frac{1}{n(n+1)}
b)Folosim punctul a)
S= \frac{1}{1} - \frac{1}{2} + \frac{1}{2} - \frac{1}{3} +...+ \frac{1}{2009} - \frac{1}{2010}\\
 S=1- \frac{1}{2010}= \frac{2009}{2010}
ultrima bucata de ce nu le-ai mai adaugat si pe 1 supra 2 +1 supara 2 si 3?