Question

calcular a soma dos termos da pg (9,-3,1,-1/3,1/9,...)

Answer 1

a1=9
n=5
q=-3/9 : 3 = -1/3 

Sn=9(-1/3^5-1)/-1/3-1
Sn=9(-1/243-1)/-1-3/3
Sn=9(-1-243/243)/-4/3
Sn=9(-244/243)/-4/3
Sn=-2196/243 : -4/3
Sn=-6588/-972   : 9

Sn=732/108 :4 

SN=-183/27 :3 

SN=-61/-9

Espero ter ajudado !