Question 1000515
Parabola shape, opening downward so the vertex is a maximum, at  (0,10).  Using behind the fence at ground level to be a zero then other side of fence where ball lands is the other zero.  These are  (-10,0) and (10,0).


The function would be  {{{p(x)=a(x+10)(x-10)}}}, and use the vertex to find the factor, a.


{{{10=a(0+10)(0-10)}}}
{{{a(10)(-10)=10}}}
{{{a=-(1/10)}}}


{{{p(x)=-(1/10)(x-10)(x+10)}}}, factored form.