document.write( "Question 872427: the next number in pattern: 3,-6,12,4,20 \n" ); document.write( "
Algebra.Com's Answer #526146 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "First thing to do is to always look for a pattern \r\n" );
document.write( "in the differences between successive terms:\r\n" );
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document.write( "2nd term - 1st term =  (-6) - (3) = -6-3 =  -9\r\n" );
document.write( "3rd term - 2nd term = (12) - (-6) = 12+6 = +18\r\n" );
document.write( "4th term - 3rd term =  (4) - (12) = 4-12 =  -8\r\n" );
document.write( "5th term - 4th term = (20) -  (4) = 20-4 = +16\r\n" );
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document.write( "So the pattern of differences go \r\n" );
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document.write( "-9, +18, -8, +16\r\n" );
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document.write( "The even term - odd term differences go  -9,  -8,  -7,  -6,  -5, ...\r\n" );
document.write( "The odd term - even term differences go +18, +16, +14, +12, +10, ...\r\n" );
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document.write( "So \r\n" );
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document.write( "6th term - 5th term = -7    \r\n" );
document.write( "      6th term - 20 = -7\r\n" );
document.write( "           6th term = 13\r\n" );
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document.write( "Edwin
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