document.write( "Question 86802: solve the equation by completeing the square\r
\n" ); document.write( "\n" ); document.write( "a2(squared)-12a+27=0
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Algebra.Com's Answer #62804 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
note: I'm going to use \"x\" instead of \"a\" as my variable\r
\n" ); document.write( "\n" ); document.write( "We can convert any quadratic \"ax%5E2%2Bbx%2Bc\" to standard vertex form \"a%28x-h%29%5E2%2Bk\" by this procedure:\r
\n" ); document.write( "\n" ); document.write( "\"y=%281%29%2Ax%5E2-%2812%29%2Ax%2B27\" Start with the given quadratic\r
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\n" ); document.write( "\n" ); document.write( "\"y-27=%281%29%2Ax%5E2-%2812%29%2Ax\" Subtract \"27\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"y-27=%281%29%2A%28x%5E2-%2812%29%2Ax%29\" Factor out the leading coefficient\"1\"
\n" ); document.write( "Now to complete the square on the right side we must take half of the x coefficient (in \"ax%5E2%2Bbx%2Bc\" its b) and square it (i.e. \"%28b%2F2%29%5E2\")\r
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\n" ); document.write( "\n" ); document.write( "\"y-27=%281%29%2A%28x%5E2-%2812%29%2Ax%2B36%29\" Take half of \"-12\" and square it (ie \"%28%28-12%29%281%2F2%29%29%5E2\"). Add the result(\"36\") just inside the parenthesis.\r
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\n" ); document.write( "\n" ); document.write( "This completes the square on the right side. So it goes from\"%281%29%2A%28x%5E2-%2812%29%2Ax%2B36%29\" and factors to \"%281%29%2A%28x-6%29%5E2\" which is a perfect square\r
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\n" ); document.write( "\n" ); document.write( "\"y-27=%281%29%2A%28x-6%29%5E2\" Factor the right side into a perfect square\r
\n" ); document.write( "\n" ); document.write( "Since we added \"36\" inside the parenthesis, we really added \"%281%29%2836%29\" to the entire right side (just distribute the leading coefficient \"1\" and you'll see it). So we must add \"%281%29%2836%29\" to the other side to balance the equation.\r
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\n" ); document.write( "\n" ); document.write( "\"y-27%2B%281%29%2A%2836%29=%281%29%2A%28x-6%29%5E2\" Add \"%281%29%2836%29\" to the other side\r
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\n" ); document.write( "\n" ); document.write( "\"y-27%2B36=%281%29%2A%28x-6%29%5E2\" Multiply\r
\n" ); document.write( "\n" ); document.write( "\"y-27%2B36=%281%29%2A%28x-6%29%5E2\" Reduce\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B9=%281%29%2A%28x-6%29%5E2\" Combine like terms on the left side\r
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\n" ); document.write( "\n" ); document.write( "\"y%2B9=%281%29%2A%28x-6%29%5E2\" Reduce any fractions left side\r
\n" ); document.write( "\n" ); document.write( "\"y=%281%29%28x-6%29%5E2-9\"Subtract \"9\" from both sides\r
\n" ); document.write( "\n" ); document.write( "So the quadratic \"y=%281%29%2Ax%5E2-%2812%29%2Ax%2B27\" is completed to \"y=%281%29%2A%28x-6%29%5E2-9\" which is now in vertex form (which is \"a%28x-h%29%5E2%2Bk\") where \"a=1\" (the stretch/compression factor), \"h=6\"(the x-coordinate of the vertex), and \"k=-9\" is the y coordinate of the vertex. So this means the vertex is (\"6\",\"-9\"). Also, since the axis of symmetry is the vertical line through the vertex, the axis of symmetry is \"x=6\" (it is equal to the x-coordinate of the vertex).\r
\n" ); document.write( "\n" ); document.write( "Here are the graphs of original quadratic \"y=%281%29%2Ax%5E2-%2812%29%2Ax%2B27\" and our answer in vertex form \"y=%281%29%28x-6%29%5E2-9\"\r
\n" ); document.write( "\n" ); document.write( " graph of \"y=%281%29%2Ax%5E2-%2812%29%2Ax%2B27\" with the vertex (\"6\",\"-9\") and the axis of symmetry \"x=6\" (it is the vertical line through the vertex)\r
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\n" ); document.write( "\n" ); document.write( " graph of \"y=%281%29%28x-6%29%5E2-9\" with the vertex (\"6\",\"-9\") and the axis of symmetry \"x=6\" (it is the vertical line through the vertex)\r
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\n" ); document.write( "\n" ); document.write( "Notice the two graphs are equivalent; this verifies our answer.\r
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\n" ); document.write( "\n" ); document.write( "Now to solve for x, we simply need to isolate x: \r
\n" ); document.write( "\n" ); document.write( "\"0=%281%29%2A%28x-6%29%5E2-9\" Set y equal to zero to solve for x\r
\n" ); document.write( "\n" ); document.write( "\"0%2B9=%281%29%2A%28x-6%29%5E2\"Add \"9\" to both sides\r
\n" ); document.write( "\n" ); document.write( "\"0%2B-sqrt%289%29=x-6\" Take the square root of both sides\r
\n" ); document.write( "\n" ); document.write( " Take the square root\r
\n" ); document.write( "\n" ); document.write( " Add \"6\" to both sides\r
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\n" ); document.write( "\n" ); document.write( "So it breaks down to this\r
\n" ); document.write( "\n" ); document.write( "\"x=6-3\" or \"x=6%2B3\"\r
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\n" ); document.write( "\n" ); document.write( "So our solution is\r
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\n" ); document.write( "\n" ); document.write( "\"x=3\" or \"x=9\"\r
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\n" ); document.write( "\n" ); document.write( "Notice if you look back at the graph, you will see the roots \"x=3\" and \"x=9\". This verifies our answer
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