👤

6+11+16+21+...+371 Ajutati-ma va rog!

Răspuns :

[371-6]/5+1=365/5+1=74      74*377/2=13949
6+11+16+21+...+371
371=6+(n-1)x5
371=6+5n-5
5n=371-6+5
n=370:5
n=74
74*377/2=13949