###### Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

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# Series and Summation Notation - Problem 10

Alissa Fong
###### Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

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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 an infinite 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 top of the sigma will have infinity, and th bottom will have your variable equal to whatever value yields the first term in your number pattern.

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