<span>y = a(x – h)2 + k</span><span>, where </span><span>(h, k)</span><span> is the vertex;
in our case, P(x) = a</span>
Δ/4a ;
a = -36; b = 900; c = -1584;
b/2a = 900/-72 = -12.5;
Δ =
4ac = 810000 - 144*1584 = 581904 => -Δ/4a = 4041;
P(x) = (-36)(x - 12.5)^2 + 4041, where (12.5 , 4041) is the vertex;