document.write( "Question 1086815: 35. Find the sum of this series: –1458 + 486 – 162 + 54 – … ; 7th term. \n" ); document.write( "

Algebra.Com's Answer #701140 by htmentor(1343) $\"\"$ $\"About$

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The sum of n terms of a geometric series is S_n = a*(1-r^n)/(1-r) where a is the 1st term and r is the common ratio.
\n" ); document.write( "This is a geometric series with r = -1/3
\n" ); document.write( "Thus S_7 = -1458*(1-(-1/3)^7)/(1-(-1/3)) = -1094 \n" ); document.write( "

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