Question

Qual e a soma dos 6 primeiros termos da P.A (1000,1300,1600,1900,2200,2500).

Answer 1

Sn = (an + a1).n/2

S6 = (2500 + 1000).6/2
S6 = 3500.6/2
S6 = 21000/2
S6 = 10500