document.write( "Question 757090: A parabola has vertex (2,4) and directrix at y=8. Find the x-intercepts of the parabola. \n" ); document.write( "
Algebra.Com's Answer #460651 by lwsshak3(11628)\"\" \"About 
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A parabola has vertex (2,4) and directrix at y=8. Find the x-intercepts of the parabola.
\n" ); document.write( "Given parabola opens downward.(directrix is above vertex on the axis of symmetry)
\n" ); document.write( "Its basic equation: (x-h)^2=-4p(y-k)
\n" ); document.write( "Given vertex: (2,4)
\n" ); document.write( "axis of symmetry: x=2
\n" ); document.write( "p=4 (distance from vertex to directrix on the axis of symmetry)
\n" ); document.write( "4p=16
\n" ); document.write( "Equation of given parabola:
\n" ); document.write( "(x-2)^2=-16(y-4)
\n" ); document.write( "To find x-intercepts, set y=0
\n" ); document.write( "(x-2)^2=-16(-4)=64
\n" ); document.write( "x-2=±√64=±8
\n" ); document.write( "x=2±8
\n" ); document.write( "x=-6, 10
\n" ); document.write( "x-intercepts are:-6 and 10 \n" ); document.write( "
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