document.write( "Question 169987: Can you please show me how to work this quadratic equation by completing the square\r
\n" ); document.write( "\n" ); document.write( "x^2 + 4x - 12 = 0
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Algebra.Com's Answer #125447 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"x%5E2%2B4x-12\" Start with the left side of the equation.\r
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\n" ); document.write( "\n" ); document.write( "Take half of the \"x\" coefficient \"4\" to get \"2\". In other words, \"%281%2F2%29%284%29=2\".\r
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\n" ); document.write( "\n" ); document.write( "Now square \"2\" to get \"4\". In other words, \"%282%29%5E2=%282%29%282%29=4\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2%2B4x%2Bhighlight%284-4%29-12\" Now add and subtract \"4\". Make sure to place this after the \"x\" term. Notice how \"4-4=0\". So the expression is not changed.\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%5E2%2B4x%2B4%29-4-12\" Group the first three terms.\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B2%29%5E2-4-12\" Factor \"x%5E2%2B4x%2B4\" to get \"%28x%2B2%29%5E2\".\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B2%29%5E2-16\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "So after completing the square, \"x%5E2%2B4x-12\" transforms to \"%28x%2B2%29%5E2-16\". So \"x%5E2%2B4x-12=%28x%2B2%29%5E2-16\".\r
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\n" ); document.write( "\n" ); document.write( "So \"x%5E2%2B4x-12=0\" is equivalent to \"%28x%2B2%29%5E2-16=0\".\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B2%29%5E2-16=0\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B2%29%5E2=0%2B16\"Add \"16\" to both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"%28x%2B2%29%5E2=16\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B2=0%2B-sqrt%2816%29\" Take the square root of both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B2=sqrt%2816%29\" or \"x%2B2=-sqrt%2816%29\" Break up the \"plus/minus\" to form two equations.\r
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\n" ); document.write( "\n" ); document.write( "\"x%2B2=4\" or \"x%2B2=-4\" Take the square root of \"16\" to get \"4\".\r
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\n" ); document.write( "\n" ); document.write( "\"x=-2%2B4\" or \"x=-2-4\" Subtract \"2\" from both sides.\r
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\n" ); document.write( "\n" ); document.write( "\"x=2\" or \"x=-6\" Combine like terms.\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So the solutions are \"x=2\" or \"x=-6\".
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