1/25+2/25+3/25+.......24/25=? Dau coroana!!!

Răspuns :

[tex]\frac{1}{25}+\frac{2}{25}+\frac{3}{25}+...+\frac{24}{25}=\\

\\ =\frac{1}{25}(1+2+3+...+24)=\\

\\ =\frac{1}{25}\cdot \frac{24\cdot 25}{2}-=\\

\\ =1\cdot \frac{24}{2}=\\

\\ =12[/tex]