PLEASE HELP QUICKLY! 30 POINTS AND WILL MARK BRAINLIEST. Write an equation for the th term of the arithmetic sequence below.
-12, -3, 6, ...

A. f(n)=-9n-21
B. f(n)=9n-21
C. f(n)=9n+21
D. f(n)=-9n+21

c

Step-by-step explanation:

you need to find how the numbers increase each time to help you.

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10