### Home > PC > Chapter 7 > Lesson 7.3.2 > Problem 7-109

7-109.

Geometric Series:

Arithmetric Series:

Use your Graphing Calculator Sum program.

Find the 20th term.

Then use the Sum formula for Arithmetic Series.

*a _{n}* =

*a*

_{1}+ (

*n*− 1)

*d*

7-109.

Geometric Series:

Arithmetric Series:

Use your Graphing Calculator Sum program.

Find the 20th term.

Then use the Sum formula for Arithmetic Series.

*a _{n}* =