Answer:
- an = 7·(-3)^(n -1)
- a5 = 567
Explanation:
You want the 5th term and the general term of an geometric sequence with a1 = 7 and r = -3.
General term
The general term of an arithmetic sequence is ...
an = a1·r^(n-1)
For a1=7 and r=-3, the general term is ...
an = 7·(-3)^(n-1)
Fifth term
Using n=5, the above equation evaluates to ...
a5 = 7·(-3)^(5 -1)
a5 = 7·(-3)^4 = 7·81
a5 = 567