Question 523948
A model rocket is launched with an initial upward velocity of 50 m/s . The rocket's height h (in meters) after t seconds is given by the following.
h=50t-5t^2

Find all values of  for which the rocket's height is  30 meters.
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{{{h = 50t - 5t^2 = 30}}}
{{{10t - t^2 = 6}}}
{{{t^2 - 10t + 6 = 0}}}
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t = (10/2) - sqrt(100 - 24)/2 seconds going up
t = 5 - sqrt(19) =~ 0.6411 seconds ascending
t = 5 + sqrt(19) =~ 9.359 seconds coming back down.