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What is the following value when expressed as a common fraction: $$\frac{1}{3^{1}}+\frac{1}{3^{2}}+\frac{1}{3^{3}}+\frac{1}{3^{4}}+\frac{1}{3^{5}}+\frac{1}{3^{6}}?$$

 Jan 25, 2015

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 #1
avatar+118696 
+10

GP

a=1/3     r= 1/3     n=6

 

\\\boxed{S_n=\frac{a(1-r^n)}{1-r}}\\\\  S_6=\frac{\frac{1}{3}(1-(\frac{1}{3})^6)}{1-\frac{1}{3}}}\\\\  S_6=\frac{\frac{1}{3}(1-\frac{1}{3^6})}{\frac{2}{3}}}\\\\  S_6=\frac{1}{\not{3}}(1-\frac{1}{3^6})\times \frac{\not{3}}{2}\\\\  S_6=\frac{1}{2}(1-\frac{1}{3^6})\\\\

 

0.5×(1(136))=364729=0.4993141289437586

 Jan 25, 2015
 #1
avatar+118696 
+10
Best Answer

GP

a=1/3     r= 1/3     n=6

 

\\\boxed{S_n=\frac{a(1-r^n)}{1-r}}\\\\  S_6=\frac{\frac{1}{3}(1-(\frac{1}{3})^6)}{1-\frac{1}{3}}}\\\\  S_6=\frac{\frac{1}{3}(1-\frac{1}{3^6})}{\frac{2}{3}}}\\\\  S_6=\frac{1}{\not{3}}(1-\frac{1}{3^6})\times \frac{\not{3}}{2}\\\\  S_6=\frac{1}{2}(1-\frac{1}{3^6})\\\\

 

0.5×(1(136))=364729=0.4993141289437586

Melody Jan 25, 2015

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