Question 871887
The given vertex (origin) and point tell you that the vertex must be a largest x value.  The value of "a" from standard form is some {{{a<0}}}.


Filling in the form, {{{x=a(y)^2}}}.
{{{a=x/(y^2)}}}
Use the point which is on the parabola;
{{{a=-2/(25)}}}.


{{{highlight(x=-(2/25)y^2)}}}