Answer: (C) -1066.65
Step-by-step explanation:
Given the sequence {-800, -200, --50, -12.5, ... , a₈} we know the following
- the first term (a₁) = -800
- the common ratio (r) = [tex]-\dfrac{1}{4}[/tex]
- the number of terms (n) = 8
Input the information above into the Sum formula:
[tex]S_n=\dfrac{a_1(1-r^n)}{1-r}\\\\S_8=\dfrac{-800(1-(\dfrac{1}{4})^8)}{1-\dfrac{1}{4}}\\\\\\.\quad =\dfrac{-800(1-\dfrac{1}{65,536})}{\dfrac{3}{4}}\\\\\\.\quad =\dfrac{-800(\dfrac{65,535}{65,536})}{\dfrac{3}{4}}\\\\\\.\quad =\dfrac{(4)(-800)(65,535)}{3(65,536)}\\\\.\quad =-1066.65[/tex]
