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What is the value of the sum $\frac{2}{3}+\frac{2^2}{3^2}+\frac{2^3}{3^3}+ \ldots +\frac{2^{10}}{3^{10}}$? Express your answer as a common fraction.

michaelcai  Oct 5, 2017
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\(\begin{align*} S &= \frac{a(1-r^{n})}{1-r}= \frac{2}{3} \cdot \frac{1-\left(\frac{2}{3}\right)^{10}}{1-\frac{2}{3}}\\ & = \frac{2}{3}\cdot\frac{1-\frac{1024}{59049}}{\frac{1}{3}}=\frac{2}{3}\cdot\frac{3}{1}\cdot\frac{58025}{59049}=\frac{2\cdot58025}{59049}\\ & = \boxed{\frac{116050}{59049}}. \end{align*}\)

michaelcai  Oct 6, 2017

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