# Chapter 12 Sequences and Series - 12.1 Define and Use Sequences and Series - 12.1 Exercises - Skill Practice - Page 798: 42

$\displaystyle \sum_{n=1}^{4}(\frac{1}{3^{n}})\qquad$or $\displaystyle \qquad\sum_{n=1}^{4}3^{-n}$

#### Work Step by Step

There are four terms, ( $\displaystyle \sum_{n=1}^{4}$... ) in which the denominators are the first four powers of 3... $a_{n}=3^{n}$ Sum = $\displaystyle \sum_{n=1}^{4}(\frac{1}{3^{n}})\qquad$or $\displaystyle \qquad\sum_{n=1}^{4}3^{-n}$

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