document.write( "Question 1204031: Suppose a parabola opens upward, has focus at (1,-1), has a horizontal directrix, and passes through the point (-31,59).\r
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Algebra.Com's Answer #840036 by MathLover1(20850)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "If the parabola is vertical, the equation of the parabola is of the form \r
\n" ); document.write( "\n" ); document.write( ".\"+y+=+a%28x+-+h%29%5E2+%2B+k\"\r
\n" ); document.write( "\n" ); document.write( "Focus (\"1\",\"-1\")= (\"h\", \"k+%2B+1%2F%284a%29+\")=> \"h=1\", \"k+%2B+1%2F%284a%29=-1\"=>\"k=-1-1%2F%284a%29\"\r
\n" ); document.write( "\n" ); document.write( "Directrix have an equation:\r
\n" ); document.write( "\n" ); document.write( " \"y+=+k+-+1%2F%284a%29\"=>\"y=-1-1%2F%284a%29-+1%2F%284a%29\"=>\"y=-1%2F%282+a%29+-+1\"\r
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\n" ); document.write( "\n" ); document.write( "\"59+=+a%28-31+-+1%29%5E2+%2B+-1-1%2F%284a%29\"\r
\n" ); document.write( "\n" ); document.write( "\"a+=+-1%2F256\"\r
\n" ); document.write( "\n" ); document.write( "or\r
\n" ); document.write( "\n" ); document.write( "\"a=1%2F16\"\r
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\n" ); document.write( "\n" ); document.write( "since given that parabola opens up, we need \"a=1%2F16\"\r
\n" ); document.write( "\n" ); document.write( "=>\"k=-1-1%2F%284%281%2F16%29%29=-5\"\r
\n" ); document.write( "\n" ); document.write( "\"y=-1%2F%282%281%2F16%29%29+-+1=-9\"\r
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\n" ); document.write( "\n" ); document.write( "a. The directrix will have an equation of\r
\n" ); document.write( "\n" ); document.write( "\"y=-9\"\r
\n" ); document.write( "\n" ); document.write( "b. The equation of the parabola will be?\r
\n" ); document.write( "\n" ); document.write( "\"y+=+%281%2F16%29%28x+-+1%29%5E2+-5\"\r
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