document.write( "Question 644483: please explain \r
\n" ); document.write( "\n" ); document.write( " b = (a^²-12)^1/2\r
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\n" ); document.write( "\n" ); document.write( " a^4 - 4a^3 - 12a^2 + 192 = 0 how this happened?
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Algebra.Com's Answer #405062 by Edwin McCravy(20081)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "a³ + b³ = 72\r\n" );
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document.write( "a³ + [(a²-12)1/2]³ = 72\r\n" );
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document.write( "a³ + (a²-12)3/2 = 72\r\n" );
document.write( "        (a²-12)3/2 = 72 - a³\r\n" );
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document.write( "Square both sides\r\n" );
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document.write( "[(a²-12)3/2]² = (72-a³)²\r\n" );
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document.write( "             (a²-12)³ =  5184-144a³+a6\r\n" );
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document.write( "(a²)³-3(a²)²(12) + 3(a²)(12) ² -(12)³ = 5184 - 144a³ + a6 \r\n" );
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document.write( "a6-36a4 + 3(a²)(144) - 1728 = 5184-144a³+a6\r\n" );
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document.write( "a6-364 + 432a² - 1728 = 5184-144a³+a6\r\n" );
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document.write( "-36a4 + 144a³ + 432a² - 6912 = 0\r\n" );
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document.write( "Divide through by -36\r\n" );
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document.write( "a4 - 4a³ - 12a² + 192 = 0\r\n" );
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document.write( "Edwin\r\n" );
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