Answer:
The sum of 8 geometric sequence is 959780
Step-by-step explanation:
We are given
this sequence is geometric
-4 , 24 , -144
First term is -4
so, [tex]a_1=-4[/tex]
now, we can find common ratio
[tex]r=\frac{24}{-4}=-6[/tex]
we can use formula
[tex]S_n=a_1(\frac{1-r^n}{1-r} )[/tex]
n=8
now, we can plug values
[tex]S_8=-4(\frac{1-(-6)^{8}}{1+6} )[/tex]
now, we can simplify it
and we get
[tex]S_8=959780[/tex]
