If you start counting from 0, you ninth term will be 8. Replace n=8 and calculate:
A(8) = -14 + (8-1)(2) = -14 + (7)(2) = -14 + 14 = 0
If you start counting from 1, your ninth term will be 9. Replace n=9 and calculate:
A(9) = -14 + (9-1)(2) = -14 + (8)(2) = -14 + 16 = 2
