### Home > PC3 > Chapter 12 > Lesson 12.1.1 > Problem 12-10

12-10.

Evaluate each the following sums.

Add the first and last terms.

Divide by.

Multiply by the number of terms.

How many terms are there?

Add the first and last terms.

Divide by.

Multiply by the number of terms.

How many terms are there? That is, if the sum started with

, what would it end with?