document.write( "Question 192645: I do not understand how to solve this problem:\r
\n" ); document.write( "\n" ); document.write( "Write the equation of the parabola with vertex (-2,-2) and directrix y=0.\r
\n" ); document.write( "\n" ); document.write( "I know that the form should be y=a(x-k)^2+k
\n" ); document.write( "and that it should be a(x+2)^2-2
\n" ); document.write( "but I don't get how to get the a.\r
\n" ); document.write( "\n" ); document.write( "Answer to problem is: -(1/8)(x+2)^2-2 \n" ); document.write( "
Algebra.Com's Answer #144608 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
Write the equation of the parabola with vertex (-2,-2) and directrix y=0.
\n" ); document.write( "I know that the form should be y=a(x-k)^2+k
\n" ); document.write( "and that it should be a(x+2)^2-2
\n" ); document.write( "but I don't get how to get the a.
\n" ); document.write( "Answer to problem is: -(1/8)(x+2)^2-2
\n" ); document.write( "-------------------------------------------
\n" ); document.write( "Starting with (x-h)^2 = 4p(y-k)
\n" ); document.write( "Since the vertex is (-2,-2) you get
\n" ); document.write( "(x+2)^2 = 4p(y+2)
\n" ); document.write( "-----------------------
\n" ); document.write( "Since the directrix is the x-axis and the vertex is 2 below it, p = -2
\n" ); document.write( "So (x+2)^2 = 4(-2)(y+2)
\n" ); document.write( "-------------
\n" ); document.write( "Solving for y you get:
\n" ); document.write( "-8(y+2) = (x+2)^2
\n" ); document.write( "y = (-1/8)(x+2)^2 -2
\n" ); document.write( "==============================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.\r
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