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5+8+11+...+305 o rezolvare va rog​

Răspuns :

Răspuns:

5+8+11+...+305

305=5+(n-1)•3

305=5+3n-3

303=3n

n=101

S101=(10+100•3)/2 • 101

S101=310/2 • 101

S101=155•101

S101=15655