document.write( "Question 771122: The problem: 2x^2 - 12x - 7 = 0
\n" ); document.write( "the directions are to solve by completing the square.
\n" ); document.write( "This is what I did:
\n" ); document.write( "2x^2 - 12x = 7
\n" ); document.write( "2x^2 - 12x + 36 = 43
\n" ); document.write( "2(x(x-6) + 18) = 43
\n" ); document.write( "x(x-6)+ 18 = (43/2)
\n" ); document.write( "x(x-6) = (7/2)
\n" ); document.write( "x^2 - 6x = (7/2)
\n" ); document.write( "I keep getting stuck
\n" ); document.write( "I know that the answers are 6.5355 and -.5355 from plugging it into the quadratic formula, but I don't know how to get there by completing the square.
\n" ); document.write( "Thank you so much for any help \n" ); document.write( "

Algebra.Com's Answer #469961 by Edwin McCravy(20055) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "2x² - 12x = 7\r\n" );
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document.write( "You didn't divide through by the coefficient of x².\r\n" );
document.write( "You must do that first:\r\n" );
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document.write( " = \r\n" );
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document.write( "x² - 6x = \r\n" );
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document.write( "Half of -6 is -3.  Square -3, (-3)² = 9,  Add 9 to both sides:\r\n" );
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document.write( "x² - 6x + 9 =  + 9\r\n" );
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document.write( "(x-3)(x-3) = \r\n" );
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document.write( "(x - 3)² = \r\n" );
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document.write( "√(x - 3)² = \r\n" );
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document.write( "x - 3 = \r\n" );
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document.write( "x - 3 = \r\n" );
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document.write( "x - 3 = \r\n" );
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document.write( "x - 3 = \r\n" );
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document.write( "x - 3 = \r\n" );
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document.write( "    x = 3  ±  \r\n" );
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document.write( "    x =   ± \r\n" );
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document.write( "    x = \r\n" );
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document.write( "That's the correct answer.\r\n" );
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\n" ); document.write( " 2x^2 - 12x = 7
\n" ); document.write( " 2x^2 - 12x + 36 = 43 <--- forgot to divide through by 2
\n" ); document.write( " 2(x(x-6) + 18) = 43 <--- shouldn't factor x out of the first two terms
\n" ); document.write( " x(x-6)+ 18 = (43/2)
\n" ); document.write( " x(x-6) = (7/2)
\n" ); document.write( " x^2 - 6x = (7/2)
\n" ); document.write( "

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document.write( "Edwin

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