Question

A geometric sequence is shown below. 3, 15, 75, 375,... What is the explicit formula for an=3⋅5nan=3⋅ an=5⋅3nan=5⋅ an=5⋅3n−1

Answer 1

The explicit formula for the given Geometric Progression is;

$\begin{gathered} a_n=ar^{n-1}\text{ , where a=3, r=}\frac{15}{3}=5,\text{ and n=?} \\ a_n=3.5^{n-1}\text{ (option C)} \end{gathered}$