# How do you find the partial sum of #Sigma (2n+5)# from n=1 to 20?

##### 2 Answers

Mar 23, 2017

#### Explanation:

The partial sum formula for n terms looks like this:

In your case, with n=20, you need to find what

When

Your formula ends up looking like this:

Mar 23, 2017

#### Explanation:

Before we proceed a few identities

Hence,

=

=

=

=

and