document.write( "Question 1182258: What number is X in this series: 101, 103, X, 115, 131? \n" ); document.write( "

Algebra.Com's Answer #812241 by Edwin McCravy(20056) $\"\"$ $\"About$

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document.write( "101, 103, X, 115, 131\r\n" );
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document.write( "Form the first differences and simplify:\r\n" );
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document.write( "103-101, X-103, 115-X, 131-115\r\n" );
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document.write( "2, X-103, 115-X, 16\r\n" );
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document.write( "Since the first and last are first and fourth powers of 2, the most likely\r\n" );
document.write( "sequence is \r\n" );
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document.write( "2, 4, 8, 16\r\n" );
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document.write( "Let's see if that works for the first differences.  If so, then this would\r\n" );
document.write( "need to be a consistent though dependent system:\r\n" );
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document.write( "They both simplify to the same equation\r\n" );
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document.write( "X = 107\r\n" );
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document.write( "That's the most likely solution for X\r\n" );
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document.write( "Checking:\r\n" );
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document.write( "101, 103, 107, 115, 131\r\n" );
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document.write( "Edwin

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