Answer:
Geometric
Step-by-step explanation:
Given terms are {3, -1, 1/3, -1/9............}
If we have common difference between the terms then it is arithmetic
If we have common ratio between the terms then it is Geometric
Difference of 3 and -1 is 4
Difference of 1/3 and -1 is -4/3
Common difference it not same so it is not Arithmetic
Now we check common ratio
we divide second term by first term
first term is 3 and second term is -1
now we check with next two terms
common ratio is -1/3
So this is Geometric