document.write( "Question 400901: graph the equation. identify the focus and directrix of the parabola, y^2=-4x \n" ); document.write( "
Algebra.Com's Answer #284038 by lwsshak3(11628)\"\" \"About 
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graph the equation. identify the focus and directrix of the parabola, y^2=-4x
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\n" ); document.write( "y^2=-4x is of the form, y^2=-4px
\n" ); document.write( "This is a parabola with horizontal axis of symmetry,y=0, opening leftward.
\n" ); document.write( "vertex (0,0)
\n" ); document.write( "4p=4
\n" ); document.write( "p=1
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\n" ); document.write( "The focus is on the line of symmetry so its y-coordinate=0
\n" ); document.write( "Its x-coordinate is \"p\" or 1 unit to the left of the vertex.
\n" ); document.write( "Therefore, the (x,y) coordinates of the focus is (-1,0)
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\n" ); document.write( "The directrix is a vertical line \"p\" or 1 unit on the right side of the vertex, that is, x=1
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\n" ); document.write( "ans: The focus is at (-1,0), and equation of the directrix is x=1\r
\n" ); document.write( "\n" ); document.write( "see the following graph\r
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