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1+2+3+...........+47+48

Răspuns :

S=48*49:2
S=24*49
S=1176
[tex]\displaystyle \frac{n(n+1)}{2} , \text{n=ultimul nr din sir.} \\ \\ 1+2+3+...........+47+48= \frac{48(48+1)}{2} = \frac{\not48\cdot49}{\not2}= 24\cdot49=1176[/tex]