Answer:
[tex]\text{ a}_n=-4\cdot(4)^{n-1}[/tex]Explanation:
The general exponential form of terms in an exponential sequence is:
[tex]\text{ a}_n=ar^{n-1}[/tex]where a is the first term, r is the common ratio and n is the term number
We already have the first term as -4
To get the common ratio, we have to divide subsequent terms as follows:
[tex]r\text{ = }\frac{-16}{-4}\text{ = }\frac{-64}{-16}\text{ = }\frac{-256}{-64}\text{ = 4}[/tex]Thus, we have the exponential function as:
[tex]\text{ a}_n=-4\cdot(4)^{n-1}[/tex]