Question

What is the explicit formula for this geometric sequence?8,4,2,1

Answer 1

C

the n th term formula ( explicit formula ) for a geometric sequence is

$a_{n}$ = $a_{1}$$(r)^{n-1}$

where r is the common ratio and $a_{1}$ the first term

here $a_{1}$ = 8 and r = $\frac{4}{8}$ = $\frac{2}{4}$ = $\frac{1}{2}$

$a_{n}$ = 8($\frac{1}{2}$)^n - 1  → C