document.write( "Question 915680: Find (a) the directrix, (b) the focus and (c) the roots of the parabola y=x^2-5x+4.\r
\n" ); document.write( "\n" ); document.write( "Help.\r
\n" ); document.write( "\n" ); document.write( "Thank you. \n" ); document.write( "
Algebra.Com's Answer #555701 by lwsshak3(11628)\"\" \"About 
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Find (a) the directrix, (b) the focus and (c) the roots of the parabola y=x^2-5x+4.
\n" ); document.write( "complete the square:
\n" ); document.write( "y=(x^2-5x+25/4)-25/4+4
\n" ); document.write( "y=(x-5/2)^2-9/4
\n" ); document.write( "(x-5/2)^2=(y+9/4)
\n" ); document.write( "This is an equation of a parabola that opens up.
\n" ); document.write( "Its basic form of equation: (x-h)^2=4p(y-k), (h,k)=coordinates of the vertex
\n" ); document.write( "For given equation:(x+(5/2))^2=(y+(9/4))
\n" ); document.write( "vertex:(5/2,-9/4)
\n" ); document.write( "axis of symmetry: x=5/2
\n" ); document.write( "4p=1
\n" ); document.write( "p=1/4
\n" ); document.write( "a)directrix:y=-10/4=-5/2
\n" ); document.write( "b)focus: (5/2,-2)
\n" ); document.write( "c) roots:
\n" ); document.write( "set y=0
\n" ); document.write( "(x-5/2)^2=(y+9/4)
\n" ); document.write( "(x-5/2)^2=9/4
\n" ); document.write( "x-5/2=±√(9/4)=±3/2
\n" ); document.write( "x=5/2±3/2
\n" ); document.write( "x=8/2=4
\n" ); document.write( "or
\n" ); document.write( "x=2/2=1 \n" ); document.write( "
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