Question

calcule a soma dos 10 primeiros termos da pg(-4,-12,-36

Answer 1

Sn=?
a1=-4
n=10
q=3

Sn=a1 (q^n-1)
---------
q -1

Sn=-4 (3^10-1)
----------
3-1
Sn= -4 (59049-1)
-------------
2

Sn= -4 (59048)
----------
2

Sn= -236192
-------------
2

Sn= 118096