document.write( "Question 1089382: Find the nth term for the following progression\r
\n" ); document.write( "\n" ); document.write( "8, 14, 22, 32, 44
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Algebra.Com's Answer #703781 by MathLover1(20850)\"\" \"About 
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\"8\", \"14\", \"22\", \"32\", \"44\" \r
\n" ); document.write( "\n" ); document.write( "find differences:
\n" ); document.write( "\"8\".........\"14\".........\"22\".........\"32\".........\"44\"
\n" ); document.write( ".....\"6\".............\"8\".........\"10\".........\"12\"
\n" ); document.write( "..............\"2\".............\"2\".........\"2\"-> second differences are constant, the sequence can be described by a quadratic formula of the form:\r
\n" ); document.write( "\n" ); document.write( "\"u%5Bn%5D=an%5E2%2Bbn%2Bc\"\r
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\n" ); document.write( "\n" ); document.write( "now find coefficients \"a\",\"+b\", and \"c\"\r
\n" ); document.write( "\n" ); document.write( "To find the values of \"a\", \"b\" and \"c\" consider the first \"3\" terms.\r
\n" ); document.write( "\n" ); document.write( "Using \"u%5B1%5D=8\" and \"n=1\" gives\r
\n" ); document.write( "\n" ); document.write( "\"8=a%2Bb%2Bc\"..........eq.1\r
\n" ); document.write( "\n" ); document.write( "Using \"u%5B2%5D=14\" and \"n=2\" gives\r
\n" ); document.write( "\n" ); document.write( "\"14=a%2A2%5E2%2Bb%2A2%2Bc\"
\n" ); document.write( "\"14=4a%2B2b%2Bc\"..........eq.2\r
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\n" ); document.write( "\n" ); document.write( "Using \"u%5B3%5D=22\" and \"n=3\" gives\r
\n" ); document.write( "\n" ); document.write( "\"22=a%2A3%5E2%2Bb%2A3%2Bc\"
\n" ); document.write( "\"22=9a%2B3b%2Bc\"..........eq.3\r
\n" ); document.write( "\n" ); document.write( "solve the system:\r
\n" ); document.write( "\n" ); document.write( "\"8=a%2Bb%2Bc\"..........eq.1
\n" ); document.write( "\"14=4a%2B2b%2Bc\"..........eq.2
\n" ); document.write( "\"22=9a%2B3b%2Bc\"..........eq.3
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\n" ); document.write( "\n" ); document.write( "start with \"8=a%2Bb%2Bc\"..........eq.1 and solve for \"c\"
\n" ); document.write( "\"c=8-b-a\"..........eq.1a\r
\n" ); document.write( "\n" ); document.write( "same with \"14=4a%2B2b%2Bc\"..........eq.2
\n" ); document.write( " \"c=14-4a-2b\" .........eq.2b\r
\n" ); document.write( "\n" ); document.write( "from eq.1a and eq.2b we have
\n" ); document.write( "\"8-b-a=14-4a-2b\"\r
\n" ); document.write( "\n" ); document.write( "\"-b-a%2B4a%2B2b=14-8\"\r
\n" ); document.write( "\n" ); document.write( "\"3a%2Bb=6\"................solve for \"b\"
\n" ); document.write( "\"b=6-3a\"...........eq.3c\r
\n" ); document.write( "\n" ); document.write( "go to \"c=8-b-a\"..........eq.1a, substitute \"b\"\r
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\n" ); document.write( "\n" ); document.write( "\"c=8-%286-3a%29-a\"
\n" ); document.write( "\"c=8-6%2B3a-a\"
\n" ); document.write( " \"c=+2%2B2a\".........eq.4d\r
\n" ); document.write( "\n" ); document.write( "take eq3c and eq.4d, and substitute it in \r
\n" ); document.write( "\n" ); document.write( "\"22=9a%2B3b%2Bc\"..........eq.3
\n" ); document.write( "\"22=9a%2B3%286-3a%29%2B2%2B2a\"
\n" ); document.write( "\"22=9a%2B18-9a%2B2%2B2a\"
\n" ); document.write( "\"22=20%2B2a\"
\n" ); document.write( "\"22-20=2a\"
\n" ); document.write( "\"2=2a\"
\n" ); document.write( "\"a=1\"\r
\n" ); document.write( "\n" ); document.write( "find \"b=6-3a\"...........eq.3c
\n" ); document.write( "\"b=6-3%2A1\"
\n" ); document.write( "\"b=3\"\r
\n" ); document.write( "\n" ); document.write( "and \"c=+2%2B2a\".........eq.4d will be
\n" ); document.write( " \"c=+2%2B2%2A1\"
\n" ); document.write( " \"c=+4\"\r
\n" ); document.write( "\n" ); document.write( "so, the nth term for the following progression is:\r
\n" ); document.write( "\n" ); document.write( "\"u%5Bn%5D+=+n%5E2+%2B+3n+%2B+4\" (for all terms given)\r
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