Re-posting because I need help.. Please help and show how you got the answer..

Answer:
Explicit: -2*2^(n-1)
Recursive: 2*aₙ₋₁
Step-by-step explanation:
To write a explicit formula for this geometric sequence you follow the following formula/template
Firstnumber*commonratio^(n-1)
Seeing that the common ratio is 2 we can start plugging numbers in and get
-2*2^(n-1)
For a recursive formula we follow the following template
common ratio * the n-1 term
So we could write this as
2*aₙ₋₁