No matter what number you choose for x, the 6(x+3)^2 term will always be positive. The lowest number that term can be is 0, in which case f = 0 - 1 = -1
Ok so using t = -b / 2*a, where b = 92 and a = -16....that gives you the time at where the ball is at max height. Plug that into the original function and you should get your answer.
Comments
i got 1983.75 but i think im wrong
i got -243 :-S