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document.write( "You need to review how to handle \"reversed differences\":\r\n" );
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document.write( "The shortcut is\r\n" );
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document.write( "
\r\n" );
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document.write( "No doubt that is why you got the sign wrong.\r\n" );
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document.write( "Anyway, let's do your problem:\r\n" );
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document.write( "
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document.write( "
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document.write( "Multiply the bottoms only:\r\n" );
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document.write( "
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document.write( "Have you learned the shortcut trick about reversed differences? \r\n" );
document.write( "That is, that (x-9) cancels into (9-x) and goes -1 times?\r\n" );
document.write( "If you have, fine, then use it. But if you haven't learned that\r\n" );
document.write( "trick, then write 9-x in descending order -x+9 then factor out -1 \r\n" );
document.write( "and get -1(x-9), like this:\r\n" );
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document.write( "Write 9-x in descending order as -x+9\r\n" );
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document.write( "
\r\n" );
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document.write( "Then factor -1 out of -x+9 which changes the signs:\r\n" );
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document.write( "
\r\n" );
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document.write( "Now you can cancel the (x-9)'s\r\n" );
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document.write( "
\r\n" );
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document.write( "
\r\n" );
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document.write( "Now you can substitute 9 for x:\r\n" );
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document.write( "
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document.write( "
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document.write( "
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document.write( "Edwin
\n" );
document.write( "![\"\"](\"/images/stars/stars-13.gif\")
