document.write( "Question 1037724: For the following arithmetic sequence, find the sum of the terms from a13
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Algebra.Com's Answer #652499 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "The sum of the first n terms\r\n" );
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document.write( "\"S%5Bn%5D=expr%28n%2F2%29%282a%5B1%5D%2B%28n-1%29d%29\"\r\n" );
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document.write( "Where a1 = first term = 7\r\n" );
document.write( "and d = common difference = a2-a1 = 10-7 = 3 = a3-a2 = \r\n" );
document.write( "13-10 = 3 = a4-a3 = 16-13 = 3\r\n" );
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document.write( "\"S%5Bn%5D=expr%28n%2F2%29%282a%5B1%5D%2B%28n-1%29d%29\"\r\n" );
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document.write( " \"%22%22=%22%22\" \"%22%22-%22%22\"\"%22%22=%22%22\"\r\n" );
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document.write( "\"S%5B21%5D\"\"%22%22-%22%22\"\"S%5B12%5D%29\"\"%22%22=%22%22\"\r\n" );
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document.write( "\"expr%2821%2F2%29%282%287%29%2B%2821-1%293%29\"\"%22%22-%22%22\"\"expr%2812%2F2%29%282%287%29%2B%2812-1%293%29\" \"%22%22=%22%22\"\r\n" );
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document.write( "\"expr%2821%2F2%29%2814%2B%2820%293%29\"\"%22%22-%22%22\"\"6%2814%2B%2811%293%29\" \"%22%22=%22%22\"\r\n" );
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document.write( "\"expr%2821%2F2%29%2814%2B60%29\"\"%22%22-%22%22\"\"6%2814%2B33%29\" \"%22%22=%22%22\"\r\n" );
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document.write( "\"expr%2821%2F2%29%2874%29\"\"%22%22-%22%22\"\"6%2847%29\" \"%22%22=%22%22\"\r\n" );
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document.write( "\"777\"\"%22%22-%22%22\"\"282\" \"%22%22=%22%22\"\r\n" );
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document.write( "\"495\" \r\n" );
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document.write( "Edwin
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