Question

The path of firework is modelled using the equation h= -5d2+20d+1 what is the maximun height?

Answer 1

$h=-5d^2+20d+1\\h'=-10d^2+20d=0\\-10d(d-2)=0\\d=0,2\\\\h=-5(2)^2+20(2)+1\\h=-5(4)+40+1\\h=-20+41\\h=21$

21 units