Question 656691
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
the vertex form of a Parabola opening right(a>0) or left(a<0), {{{x=a(y-k)^2 +h}}}
 where(h,k) is the vertex and  y = k  is the Line of Symmetry
The standard form is {{{(y -k)^2 = 4p(x -h)}}}, where  the focus is (h +p,k )
parabola with its vertex at (-1, 2) and its focus at (4, 2) 
{{{(y -2)^2 = 4p(x+1)}}}, {{{-1 + p = 4}}},  p = 5,  4p = 20
{{{(y -2)^2 = 20(x+1)}}},  
{{{drawing(300,300,   -6, 6, -6, 6,  grid(1),
circle(-1, 2,0.3),
circle(4, 2,0.3),
graph( 300, 300, -6, 6, -6, 6,0,2, sqrt(20(x+1)) + 2,-sqrt(20(x+1)) + 2))}}}