document.write( "Question 1022547: The sum of the first and last terms of a linear sequence is 42. If the sum of all the terms is 420 and the second term is 4, find
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Algebra.Com's Answer #638208 by ikleyn(52790) $\"\"$ $\"About$

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\n" ); document.write( "The sum of the first and last terms of a linear sequence is 42. If the sum of all the terms is 420 and the second term is 4, find $\"highlight%28what%29\"$ .
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document.write( "Use this formula for the sum of arithmetic progression:\r\n" );
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document.write( " = . \r\n" );
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document.write( "(see the lesson Arithmetic progressions in this site).\r\n" );
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document.write( "Then you get \r\n" );
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document.write( " =   --->   n = 20.\r\n" );
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document.write( "Next, from the condition you have these two equations\r\n" );
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document.write( " +  = 42,\r\n" );
document.write( " = ,\r\n" );
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document.write( "or\r\n" );
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document.write( " +  = ,\r\n" );
document.write( " = ,\r\n" );
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document.write( "or\r\n" );
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document.write( " +  = ,\r\n" );
document.write( " = .\r\n" );
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document.write( "The solution of this system is  = 2, d = 2.\r\n" );
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document.write( "Get it by any method.\r\n" );
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document.write( "Do not use the term \"a linear sequence\".\r\n" );
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document.write( "Use the commonly accepted term \"arithmetic progression\".\r\n" );
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