document.write( "Question 453794: solve by completing the square.\r
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Algebra.Com's Answer #853393 by ikleyn(53571) $\"\"$ $\"About$

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\n" ); document.write( "Solve by completing the square.
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\n" ); document.write( "\n" ); document.write( "        In his post, @mananth found one root, but missed/lost another root.\r
\n" ); document.write( "\n" ); document.write( "        So, his solution is incomplete.\r
\n" ); document.write( "\n" ); document.write( "        I came to bring a complete solution.\r
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document.write( "x^2 + 4x - 12 = 0\r\n" );
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document.write( "x^2 + 4x = 12\r\n" );
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document.write( "x^2 + 4x + 4 = 12 + 4\r\n" );
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document.write( "(x+2)^2 = 16\r\n" );
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document.write( "x + 2 = +/- \r\n" );
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document.write( "x + 2 = +/- 4\r\n" );
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document.write( "Case (a).  x + 2 = 4  --->  x = 4 - 2 = 2.\r\n" );
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document.write( "Vase (b).  x + 2 = -4 --->  x = -4 - 2 = -6.\r\n" );
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document.write( "Thus, equation  x^2 + 4x - 12 = 0  has two roots:  x = 2  and  x = -6.\r\n" );
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document.write( "Substitute these values into the equation to make sure that they do satisfy this equation.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved correctly and completely.\r
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