document.write( "Question 1126514: Find S15 for the series -1 + -3 + -5 + -7 +... \n" ); document.write( "

Algebra.Com's Answer #742941 by ikleyn(52790) $\"\"$ $\"About$

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document.write( "= - (1 + 3 + 5 + 7 + . . . ) =  = .\r\n" );
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document.write( "HINT.  The sum of the first n odd positive integer numbers is equal to .\r\n" );
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\n" ); document.write( "\n" ); document.write( "See the lessons\r
\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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