document.write( "Question 403685: find the equation of a parabola given 2 points on the parabola, (5,9)&(1,9), and the directrix d:y=-1 . \n" ); document.write( "

Algebra.Com's Answer #287051 by lwsshak3(11628) $\"\"$ $\"About$

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find the equation of a parabola given 2 points on the parabola, (5,9)&(1,9), and the directrix d:y=-1
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\n" ); document.write( "\n" ); document.write( "since the directrix=-1, the parabola opens upward.
\n" ); document.write( "The standard form of a parabola is, y=(x-h)^2+k, (h,k) being the coordinates of the vertex. Based on the given points,(5,9) and (1,9), the axis of symmetry is between x=1 and x=5, which places it at x=3, the x coordinate of the vertex. The y-coordinate is somewhere on this line.\r
\n" ); document.write( "\n" ); document.write( "Using either of the given points,
\n" ); document.write( "y=(x-h)^2+k
\n" ); document.write( "9=(5-3)^2+k
\n" ); document.write( "9=2^2+k
\n" ); document.write( "k=5
\n" ); document.write( "equation of the parabola: y=(x-3)^2+5\r
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\n" ); document.write( "\n" ); document.write( " $\"+graph%28+300%2C+200%2C+-6%2C+10%2C+-10%2C+20%2C+%28x-3%29%5E2%2B5%29+\"$ \n" ); document.write( "

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