Question

calcule a soma dos 6 primeiros termos da pg(-2,4,-8,...)

Answer 1

S = a₁ (qⁿ - 1) / q - 1

S = -2 ( -2⁶ - 1 ) / -2 - 1

S = -2 (64 -1) / -3

S = -2 (63) / -3

S = - 126 / -3

S = 42----->  resposta

{-2 ;+4;-8;+16;-32;+64}