document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=475247>Question 475247</A>: <I><SPAN STYLE=\"word-break: break-all;\"> What is the directrix of the parabola with equation 36x = 9y2? show work please  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #325870 by </B><A HREF=/tutors/aboutme.mpl?userid=robertb><B>robertb(5830)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=robertb><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=robertb><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=325870\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The standard form of the parabola is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4c%28x-h%29+=+%28y-k%29%5E2 ALIGN=MIDDLE  ALT=\"4c%28x-h%29+=+%28y-k%29%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, where (h,k) is the vertex, and c is the directed distance between the focus and the vertex.<BR>\n" );
document.write( "==> the vertex is (0,0), the equation is equivalent to <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4x+=+y%5E2 ALIGN=MIDDLE  ALT=\"4x+=+y%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, and 4c = 4.<BR>\n" );
document.write( "==> c = 1.\r<BR>\n" );
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document.write( "Since the directrix has the same (absolute) distance as the focus from the vertex, but located on the opposite side of the vertex, the directrix is the (vertical) line x = -1. </SPAN>\n" );
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