Answer:
C(1)=13
c(n)=c(n-1)+-7
Step-by-step explanation:
To find what C(1) equals look at the first number in the sequence in this case the sequence starts at 13 that's what C(1) equals
13,6,-1,-8
To find what c(n) equals you check what the common difference is in this case they are adding -7 or subtracting 7 each time.
13-7=6
6-7= -1
-1-7=-8
Then you plug the common difference into the last part it, C(n)=c(n-1)+-7
