Question

Doar exercițiul 3 va rog ​

Answer 1

$N = \sum_{n=1}^{1999} \frac{1}{n(n+1)} =  \sum_{n=1}^{1999} (\frac{1}{n} - \frac{1}{n+1}) = 1 -  \frac{1}{2000} = \frac{1999}{2000} => N < 1$