Question 923916
the vertex form of a Parabola opening up(a>0) or down(a<0),
 {{{y=a(x-h)^2 +k}}} where(h,k) is the vertex 
.....
V(-1/2, 0) 
{{{y=a(x-1/2)^2 + 0}}}
{{{y=a(x-1/2)^2}}}
....three examples
y = (x-1/2)^2 (Green)
y = -(x-1/2)^2 (Blue)
y = 2(x-1/2)^2 (Purple)
{{{drawing(300,300,   -6, 6, -6, 6, grid(1), 
circle(-.5, 0,0.2),
graph( 300, 300, -6, 6, -6, 6,0, (x-1/2)^2,-(x-1/2)^2, 2(x-1/2)^2 ) )}}}