Question

vă rooooog urgeeeeeeennnnnnttttttttttttttt ajutați-mă dau coroana+inima+ma abonez la cel care imi răspunde urgeeeeentttt ​

Answer 1

vezi atașament

uite formulele:

$1 + 2 + 3 + ... + n = \frac{n(n + 1)}{2}$

$\frac{1}{1 \times 2} + \frac{1}{2 \times 3} + ... + \frac{1}{n(n + 1)} = \frac{1}{n} - \frac{1}{n + 1}$