document.write( "Question 1158910: find the sum of the following series\r
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Algebra.Com's Answer #781889 by ikleyn(52794)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "If you don't know the formula for the sum of an arithmetic progression,\r
\n" ); document.write( "\n" ); document.write( "you have a happy opportunity to learn it from the lessons\r
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\n" ); document.write( "\n" ); document.write( "    - Arithmetic progressions\r
\n" ); document.write( "\n" ); document.write( "    - The proofs of the formulas for arithmetic progressions \r
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\n" ); document.write( "\n" ); document.write( "in this site  (on the free of charge basis).\r
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\n" ); document.write( "\n" ); document.write( "If,  in opposite,  you DO know this formula,  then do this job on your own.\r
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