Series and Summation Notation - Problem 9

The capital Greek letter Sigma is used to represent a sum. The number on the bottom of the sigma tells you the lowest value to substitute in for the variable, and the value on top tells you the last value to substitute. To write a finite geometric series in sigma notation, first determine what the first term and r values are. Then write the sigma with the explicit geometric formula next to it. The bottom of your sigma will have your variable equal to whatever value yields the first term in your number pattern, and the number on top is the last value that you'll need to substitute to get your final term.