document.write( "Question 1186602: 51, 53, 56, 60 what comes next? 51, 53, 56, 60, __, __ \n" ); document.write( "
Algebra.Com's Answer #817534 by MathLover1(20850)\"\" \"About 
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sequence : \"51\".....\"53\"....\"56\".....\"60\"
\n" ); document.write( "First diff. : .....\"2\"......\"3\".....\"4\"
\n" ); document.write( "Second diff. : ......\"1\"....\"1\" \r
\n" ); document.write( "\n" ); document.write( " We see that the second differences (blue ones) are all equal so we concludet that this is a quadratic sequence.\r
\n" ); document.write( "\n" ); document.write( "The quadratic sequence has the form \"T%5Bn%5D=an%5E2%2Bbn%2Bc\"\r
\n" ); document.write( "\n" ); document.write( "To find the value of \"a\" we just divide second difference ( \"1\" ) by \"2\".\r
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\n" ); document.write( "\n" ); document.write( " \"a=1%2F2\" \r
\n" ); document.write( "\n" ); document.write( "Now we have: \"T%5Bn%5D=%281%2F2%29n%5E2%2Bbn%2Bc\"\r
\n" ); document.write( "\n" ); document.write( "Substitute \"n=1\" and \"n=2\" into above equation:\r
\n" ); document.write( "\n" ); document.write( "\"T%5B1%5D=%281%2F2%291%5E2%2Bb%2A1%2Bc\"\r
\n" ); document.write( "\n" ); document.write( "\"T%5B2%5D=%281%2F2%292%5E2%2Bb%2A2%2Bc\"
\n" ); document.write( "---------------------------------------- Since \"T%5B1%5D=51\" and \"T%5B2%5D=53\", we have\r
\n" ); document.write( "\n" ); document.write( "\"51=1%2F2%2Bb%2Bc\"....eq.1\r
\n" ); document.write( "\n" ); document.write( "\"53=2%2B2b%2Bc\".............e.2
\n" ); document.write( "---------------------------------------subtract eq.1 from eq.2\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"53-51=2%2B2b%2Bc-%281%2F2%2Bb%2Bc%29\"
\n" ); document.write( "\"2=2%2B2b%2Bc-1%2F2-b-c\"\r
\n" ); document.write( "\n" ); document.write( "\"2=3%2F2%2Bb\"....... solve for \"b\"\r
\n" ); document.write( "\n" ); document.write( "\"2-3%2F2=b\"\r
\n" ); document.write( "\n" ); document.write( "\"b=1%2F2\"\r
\n" ); document.write( "\n" ); document.write( "go to\r
\n" ); document.write( "\n" ); document.write( "\"51=1%2F2%2Bb%2Bc\"....eq.1, substitute\"+b\"\r
\n" ); document.write( "\n" ); document.write( "\"51=1%2F2%2B1%2F2%2Bc\"....... solve for \"c\"\r
\n" ); document.write( "\n" ); document.write( "\"51=1%2Bc\"\r
\n" ); document.write( "\n" ); document.write( "\"c=51-1\"\r
\n" ); document.write( "\n" ); document.write( "\"c=50\"\r
\n" ); document.write( "\n" ); document.write( "and, your nth term formula is: \"T%5Bn%5D=%281%2F2%29n%5E2%2B%281%2F2%29n%2B50\"\r
\n" ); document.write( "\n" ); document.write( "then next term will be 5th term, means \"n=5\"\r
\n" ); document.write( "\n" ); document.write( "\"T%5B5%5D=%281%2F2%295%5E2%2B%281%2F2%295%2B50\"\r
\n" ); document.write( "\n" ); document.write( "\"T%5B5%5D=65\"\r
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