### Home > CC4 > Chapter 11 > Lesson 11.1.3 > Problem 11-33

11-33.

How many terms are in the arithmetic sequence shown below? Homework Help ✎

15, 7, −1, −9, ..., −225

Write an equation for the arithmetic sequence using *a _{n}* −

*m*(

*n*− 1) +

*a*

_{1}

Let *a _{n}* = −225 and solve for

*n*.