document.write( "Question 130757: Using $\"f%28x%29=-2x%5E2%2B2x%2B8\"$ , find the x-coordinate of the vertex and the equation of the line of symmetry. \n" ); document.write( "

Algebra.Com's Answer #95469 by jim_thompson5910(35256) $\"\"$ $\"About$

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To find the x-coordinate of the vertex, we can use this formula:\r
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\n" ); document.write( "\n" ); document.write( " $\"x=-b%2F%282a%29\"$ \r
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\n" ); document.write( "\n" ); document.write( "From the equation $\"f%28x%29=-2x%5E2%2B2x%2B8\"$ we can see that a=-2 and b=2\r
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\n" ); document.write( "\n" ); document.write( " $\"x=%28-2%29%2F%282%2A-2%29\"$ Plug in b=2 and a=-2\r
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\n" ); document.write( "\n" ); document.write( " $\"x=%28-2%29%2F-4\"$ Multiply 2 and -2 to get -4\r
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\n" ); document.write( "\n" ); document.write( " $\"x=1%2F2\"$ Reduce\r
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\n" ); document.write( "\n" ); document.write( "So the x-coordinate of the vertex is $\"x=1%2F2\"$ \r
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\n" ); document.write( "\n" ); document.write( "In turn, this means that the equation of the line of symmetry is also $\"x=1%2F2\"$ (since the line goes through the vertex)\r
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