Home > CCA2 > Chapter 10 > Lesson 10.1.2 > Problem10-35

10-35.

Consider the series $21+17+13+\dots+-99$ as you answer the questions in parts (a) through (c) below.

1. Write an expression for the $n$th term.

Use a system of equations or look at the difference between terms and the value of the first term.

2. How many terms are in the series? How can you tell?

Set the equation you found in part (a) equal to $-99$ and solve for $n$.

3. What is the sum of this series?

Use the rectangle method or Antonio's method.

$-1209$