Question 411661
{{{ f(t)=-16t^2 + 96t}}}
{{{144 = -16t^2 + 96t}}}
{{{-16t^2 + 96t - 144 = 0}}}
{{{-t^2 + 6t - 9 = 0}}}
{{{(-t + 3)*(t - 3) = 0}}}  (I just figured it out- pretty simple)
{{{t = 3}}}
The answer is (b)
check answer:
{{{144 = -16*3^2 + 96*3}}}
{{{144 = -144 + 288}}}
{{{144 = 144}}}
OK