Question

2438+2440+2442+...+3710= (asta e primul)

2439+2441+2443+...+3711= (al doilea)

Answer 1

S1 = (2438+2·0) +(2438+2·1)+(2438+2·2)+..............+(2438+2·636)
S = 2438·637 +2·(1+2+3+..........+636) = 2438·637 + 2·636·637/2 =637(2438+636) =637·3074 = 1958138
S2 = (2439+2·0)+(2439+2·1)+(2439+2·2)+........+(2439+2·636) = 2439·637 + +2(1+2+3+..........+636) = 2439·637 + 2·636·637/2 = 637(2439+636)= 637·3075 = 1958775