Consider the series 21 + 17 + 13 + … + −99 as you answer the questions in parts (a) through (c) below. Homework Help ✎
Write an expression for the nth term.
How many terms are in the series? How can you tell?
What is the sum of this series?
Use a system of equations or look at the difference between terms and the value of the first term.
Set the equation you found in part (a) equal to −99 and solve for n.
Use the rectangle method or Antonio's method.