Answer
The recursive formula is $a_{1}$=4 and $a_{n}$=$a_{n-1}$ $\times$ 2.
Work Step by Step
Use the recursive formula $a_{1}$=1, $a_{n}$=$a_{n-1}$$\times$r.
The starting value is 4, so it is the $a_{1}$.
You have the sequence 4,8,16 so use the common ratio formula(r=$\frac{{a_{2}}}{{a_{1}}}$) r=$\frac{8}{4}$=2 and r=$\frac{16}{8}$=2.So the common ratio is 2.Substitute the value of a1 and R into the recursive formula:
The recursive formula is $a_{1}$=4 and $a_{n}$=$a_{n-1}$ $\times$ 2.
