document.write( "Question 83343: Complete the square: 2x^2+10x+11=0 \n" ); document.write( "
Algebra.Com's Answer #59834 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Completing the Square to Get a Quadratic into Vertex Form

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\n" ); document.write( " \"y=2+x%5E2%2B10+x%2B11\" Start with the given equation
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\n" ); document.write( " \"y-11=2+x%5E2%2B10+x\" Subtract \"11\" from both sides
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\n" ); document.write( " \"y-11=2%28x%5E2%2B5x%29\" Factor out the leading coefficient \"2\"
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\n" ); document.write( " Take half of the x coefficient \"5\" to get \"5%2F2\" (ie \"%281%2F2%29%285%29=5%2F2\").
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\n" ); document.write( " Now square \"5%2F2\" to get \"25%2F4\" (ie \"%285%2F2%29%5E2=%285%2F2%29%285%2F2%29=25%2F4\")
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\n" ); document.write( " \"y-11=2%28x%5E2%2B5x%2B25%2F4-25%2F4%29\" Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of \"25%2F4\" does not change the equation
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\n" ); document.write( " \"y-11=2%28%28x%2B5%2F2%29%5E2-25%2F4%29\" Now factor \"x%5E2%2B5x%2B25%2F4\" to get \"%28x%2B5%2F2%29%5E2\"
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\n" ); document.write( " \"y-11=2%28x%2B5%2F2%29%5E2-2%2825%2F4%29\" Distribute
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\n" ); document.write( " \"y-11=2%28x%2B5%2F2%29%5E2-25%2F2\" Multiply
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\n" ); document.write( " \"y=2%28x%2B5%2F2%29%5E2-25%2F2%2B11\" Now add \"11\" to both sides to isolate y
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\n" ); document.write( " \"y=2%28x%2B5%2F2%29%5E2-3%2F2\" Combine like terms
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\n" ); document.write( " Now the quadratic is in vertex form \"y=a%28x-h%29%5E2%2Bk\" where \"a=2\", \"h=-5%2F2\", and \"k=-3%2F2\". Remember (h,k) is the vertex and \"a\" is the stretch/compression factor.
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\n" ); document.write( " Check:
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\n" ); document.write( " Notice if we graph the original equation \"y=2x%5E2%2B10x%2B11\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C2x%5E2%2B10x%2B11%29\" Graph of \"y=2x%5E2%2B10x%2B11\". Notice how the vertex is (\"-5%2F2\",\"-3%2F2\").
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\n" ); document.write( " Notice if we graph the final equation \"y=2%28x%2B5%2F2%29%5E2-3%2F2\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C2%28x%2B5%2F2%29%5E2-3%2F2%29\" Graph of \"y=2%28x%2B5%2F2%29%5E2-3%2F2\". Notice how the vertex is also (\"-5%2F2\",\"-3%2F2\").
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\n" ); document.write( " So if these two equations were graphed on the same coordinate plane, one would overlap another perfectly. So this visually verifies our answer.
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