document.write( "Question 40448: using the formulas for parabolas, graph and write the equations of parabolas with the following properties. Graph an extra point other than a vertex. The Parabola with focus (0, 5) and directrix y= -5. \n" ); document.write( "
Algebra.Com's Answer #25819 by Nate(3500)\"\" \"About 
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From the information we can tell that the vertex is at the origin.
\n" ); document.write( "P = 1/(4a) when \"P\" is the distance from the vertex to the focus and from the vertex to the directrix
\n" ); document.write( "5 = 1/(4a)
\n" ); document.write( "20a = 1
\n" ); document.write( "a = (1/20)
\n" ); document.write( "Use:
\n" ); document.write( "\"y+=+a%28x+-+h%29%5E2+%2B+k\"
\n" ); document.write( "\"y+=+%281%2F20%29%28x%29%5E2\"
\n" ); document.write( "For another point, pick \"x+=+1\" ....
\n" ); document.write( "\"y+=+%281%2F20%29%281%29%5E2\"
\n" ); document.write( "\"y+=+%281%2F20%29\"
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Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation \"ax%5E2%2Bbx%2Bc=0\" (in our case \"0.05x%5E2%2B0x%2B0+=+0\") has the following solutons:
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\n" ); document.write( " \"x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca\"
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\n" ); document.write( " For these solutions to exist, the discriminant \"b%5E2-4ac\" should not be a negative number.
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\n" ); document.write( " First, we need to compute the discriminant \"b%5E2-4ac\": \"b%5E2-4ac=%280%29%5E2-4%2A0.05%2A0=0\".
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\n" ); document.write( " Discriminant d=0 is zero! That means that there is only one solution: \"x+=+%28-%280%29%29%2F2%5C0.05\".
\n" ); document.write( " Expression can be factored: \"0.05x%5E2%2B0x%2B0+=+0.05%28x-0%29%2A%28x-0%29\"
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\n" ); document.write( " Again, the answer is: 0, 0.\n" ); document.write( "Here's your graph:
\n" ); document.write( "\"graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+0.05%2Ax%5E2%2B0%2Ax%2B0+%29\"
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