document.write( "Question 1092279: The sum of the first two terms of an arithmetic progression is 23. The sum of
\n" ); document.write( "the last two terms is -25. Find the sum of the progression if its first term is 13. \n" ); document.write( "

Algebra.Com's Answer #706881 by ikleyn(52800) $\"\"$ $\"About$

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document.write( "The first term is 23 - 13 = 10.\r\n" );
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document.write( "The common difference is -3.\r\n" );
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document.write( "The equation for the last term, x, is  \r\n" );
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document.write( "x + (x+3) = -25,\r\n" );
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document.write( "which implies  2x = -28, x = -14.\r\n" );
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document.write( "So, the progression is 13, 10, 7, 4, 1, -2, -5, -8, -11, -14.\r\n" );
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document.write( "10 terms with the sum of -5.\r\n" );
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