Question 763418
Your solution is right. The quadratic has two roots x = 0 and x = 12.

See the graph below (I have divided the eqn by 25 to make -x^2 + 12*x = 0, which has the same 2 roots, to make it fit.) You are right that the graph opens downwards. It has a max value for x = 6.


:)

{{{graph( 600, 600, -20, 20, -50, 50, -x^2 + 12*x + 0)}}}