Question

Calcule a soma dos 6 primeiros termos da PG ( -2,4,-8 ).

Answer 1

an= -2.-2^6-1
an= -2.-2^5
an= -2.-32
an= 64

Sn= ( 64.(-2)-(-2)/-2-1
Sn= ( -128+2)/-3
Sn= -126/-3
Sn= 42

Resposta: 42