Answer:716,144
Step-by-step explanation:
Given
No of the terms in GP [tex]n=8[/tex]
First-term [tex]a=-11[/tex]
last term [tex]a_n=859,375\quad (ar^{n-1})[/tex]
Common ratio [tex]r=-5[/tex]
The Sum of a GP is given by
[tex]S_n=\dfrac{a(1-r^n)}{1-r}\quad \quad [r<1][/tex]
Put the values
[tex]\Rightarrow S_n=\dfrac{-11(1-(-5)^8)}{1-(-5)}\\\\\Rightarrow S_n=\dfrac{-11\times -390624}{6}\\\\\Rightarrow S_n=\dfrac{42,96,864}{6}=716,144[/tex]
