Answer
$87,380$
Work Step by Step
$\dfrac{a_{n+1}}{a_n}=\dfrac{4^{n+1}}{4^n}=4$
Since the ratio between consecutive terms is constant, the given sequence is geometric.
The first term is $a_1=4^1=4$.
The common ratio is $r=4$.
The formula for the finite sum of the geometric sequence is:
$S_{n}=\frac{a_{1}(1-r^{n})}{1-r}$
$S_{8}=\frac{4(1-4^{8})}{1-4}=87,380$
