### Home > CALC > Chapter 2 > Lesson 2.1.3 > Problem 2-41

2-41.

Rewrite the following sums using summation notation. Homework Help ✎

5 + 7 + 9 + 11 + 13

2 cos 2

*π*+ 3 cos 3*π*+ 4 cos 4*π*+ 5 cos 5*π*

Answers vary. Here are three possible answers.

Notice the index of all answers: every index has exactly 5 terms... because there are exactly 5 terms in the series.

Complete the argument:

Complete the index: