<PRE><B>Question 180859</B>
Rewrite this equation as 


h =-16t^2 + 40t 


It is well-known that the highest point on a parabolic graph y=ax^2 +bx +c occurs at the value of {{{x = -b/(2a)}}}.


In this equation for h=-16t^2 + 40t, the maximum value of h occurs when 
{{{t=-b/(2a) }}}
{{{t=(-40)/(2*-16) }}}
{{{t=(-40)/(-32)}}}
{{{t=10/8=5/4}}} seconds


R^2</PRE>