document.write( "Question 603295: How do you factor second degree polynomials? Then how do you know if it's addition or subtraction?
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Algebra.Com's Answer #380647 by Edwin McCravy(20086)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "x²-18x+45\r\n" );
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document.write( "Write this:\r\n" );
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document.write( "(x    )(x   )\r\n" );
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document.write( "List all the ways to factor 45, starting with 45*1  \r\n" );
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document.write( "45*1=45\r\n" );
document.write( "15*3=45\r\n" );
document.write( " 9*5=45\r\n" );
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document.write( "The last sign is +  (from +45), so out beside them, ADD them:\r\n" );
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document.write( "45*1=45  45+1=46\r\n" );
document.write( "15*3=45  15+3=18\r\n" );
document.write( " 9*5=45   9+5=14\r\n" );
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document.write( "We see that 15+3 was 18, the absolute value of the middle\r\n" );
document.write( "coefficient, so we fill in these\r\n" );
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document.write( "(x 15)(x 3)\r\n" );
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document.write( "We do a mental FOIL ignoring signs\r\n" );
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document.write( "Since the last sign is +, both signs have the same sign, the same\r\n" );
document.write( "sign as the middle term -18x, which is -, so the answer is\r\n" );
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document.write( "(x-15)(x-3)\r\n" );
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document.write( "-------------------------\r\n" );
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document.write( "Another example:\r\n" );
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document.write( "x²+3x-28\r\n" );
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document.write( "Write this:\r\n" );
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document.write( "(x  )(x  )\r\n" );
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document.write( "List all the ways to factor 28 starting with 28*1\r\n" );
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document.write( "28*1=28\r\n" );
document.write( "14*2=28\r\n" );
document.write( " 7*4=28\r\n" );
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document.write( "The last sign is -  (from -28), so out beside them, SUBTRACT them:\r\n" );
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document.write( "28*1=28  28-1=27\r\n" );
document.write( "14*2=28  14-2=12\r\n" );
document.write( " 7*4=28   7-4=3\r\n" );
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document.write( "We see that 7-4 was 3, the absolute value of the middle coefficient,\r\n" );
document.write( "so we fill in these\r\n" );
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document.write( "(x 7)(x 4)\r\n" );
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document.write( "We do a mental FOIL ignoring signs\r\n" );
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document.write( "Since the last sign is -, the signs are opposite, so the LARGER,\r\n" );
document.write( "which is 7, gets the same sign as the middle term +3x, which is +, so the answer is\r\n" );
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document.write( "(x+7)(x-4)\r\n" );
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document.write( "Edwin
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