Question 459071
{{{ h = -16t2 + 96t }}}
{{{ 144 = -16t^2 + 96t }}}
{{{ -16t^2 + 96t - 144 = 0 }}}
{{{ -t^2 + 6t - 9 = 0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
{{{ a = -1 }}}
{{{ b = 6 }}}
{{{ c = -9 }}}
{{{ t = (-6 +- sqrt( 36 - 4*(-1)*(-9) ))/(2*(-1)) }}}
{{{ t = (-6 +- sqrt( 36 - 36 )) / (-2) }}}
{{{ t = (-6) / (-2) = 3 }}}
It takes 3 sec to reach a height of 144 ft