### Home > CCA > Chapter 10 > Lesson 10.2.3 > Problem 10-56

10-56.

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* sub *n* = −225 and solve for *n*.