document.write( "Question 393129: write the quadratic equation which has 7 and -3 as its roots \n" ); document.write( "
Algebra.Com's Answer #279058 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "You do a problem like this by \"solving it backwards\",\r\n" );
document.write( "starting with the solution and going backward to the problem.\r\n" );
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document.write( "If you had solved such an equation and ended up with\r\n" );
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document.write( "x = 7 and x = -3 \r\n" );
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document.write( "then before that you would have had\r\n" );
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document.write( "x - 7 = 0 and x + 3 = 0\r\n" );
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document.write( "then before that you would have had\r\n" );
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document.write( "(x - 7)(x + 3) = 0\r\n" );
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document.write( "then before that you would have had\r\n" );
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document.write( "x² - 4x - 21 = 0\r\n" );
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document.write( "-------------------------------------------\r\n" );
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document.write( "Check it by solving forward:\r\n" );
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document.write( "x² - 4x - 21 = 0\r\n" );
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document.write( "(x - 7)(x + 3) = 0\r\n" );
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document.write( "x - 7 = 0 and x + 3 = 0\r\n" );
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document.write( "    x = 7 and x = -3\r\n" );
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document.write( "It checks when solved forward, so the correct\r\n" );
document.write( "equation is\r\n" );
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document.write( "x² - 4x - 21 = 0\r\n" );
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document.write( "Edwin
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