Question 1172180
h(t)=-5t^2+10t+20
maximum height is where t=-b/2a or -10/-10 or 1 second after leaving.
that is 25 feet high.
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set the equation equal to 0
-5(t^2-2t-4)=0
t=(1/2)(2+/- sqrt 20); sqrt (20) is 2 sqrt(5), the numerator 2s cancel
=1+/-sqrt(5)
3.236 seconds, only positive root
{{{graph(300,300,-4,4,-10,30,-5x^2+10x+20,25)}}}