Question

calcule a soma dos 7 primeiros termos da p.g (8;4;2;1;1/2)

Answer 1

s₇ = 8 [(1/2)^7 -1]/1/2 -1
s₇ = -4 [1/128 -1]
s₇ =  -4 .  -127/128
s₇ = 508/128 ⇒ 127/32