What is the formula for the following arithmetic sequence?

-9, - 2, 5, 12, ...

an = 9 + (-7) (n - 1)

an = - 9 + 7 (n - 1)

an = 7 + (-9) (n - 1)

an = - 9 + (-7) (n - 1)

an = - 9 + 7 (n - 1)

Step-by-step explanation:

an = first term + difference (n-1)

First term = 9

Difference = - 2 - - 9 = - 2 + 9 = 7

an = - 9 + 7 (n - 1)

You can check this by substituting the values in.

a1 = - 9 + 7 (0) = - 9

a2 = - 9 + 7 (2) = - 9 + 7 = - 2

a3 = - 9 + 7 (3) = - 9 + 14 = 5