Question 1091736
y=-(1/2)x^2
vertex has x value of -b/2a.  But there is no b, so vertex has x value of 0, and y value of 0. The origin.
when x=1 or -1, y=-1/2
when x=2 or -2, y=-2
{{{graph(300,300,-10,10,-10,10,-(1/2)x^2)}}}