document.write( "Question 855498: The fiveth and tenth terms of an AP are 12ft and 27ft respectively.Find the AP and is 15th
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Algebra.Com's Answer #515397 by ramkikk66(644) $\"\"$ $\"About$

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document.write( "Let a be the first term of the AP and d be the common difference (i.e.\r\n" );
document.write( "difference between any 2 consecutive terms)\r\n" );
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document.write( "nth term of an AP is given by a + (n - 1)*d\r\n" );
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document.write( "5th term = a + 4*d = 12 --- (1)\r\n" );
document.write( "10th term = a + 9*d = 27 --- (2)\r\n" );
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document.write( "Subtracting 1st equation from 2nd, we get\r\n" );
document.write( "5*d = 15 or d = 3\r\n" );
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document.write( "Substituting for d in (1), we get a + 4*3 = 12, or a = 0.\r\n" );
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document.write( "So the 1st term of the AP is 0, and common difference is 3.\r\n" );
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document.write( "15th term = a + 14*d = 0 + 14*3 = \r\n" );
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document.write( "Hope this helps :)\r\n" );
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