Question 829633
the height in feet of a bottle rocket is given by h(t)=160t-t2 where t is the time in seconds. How long will it take for the rocket to return to the ground?
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{{{h(t) = 160t - t^2}}}
At impact, h(t) = 0
Solve for t.  You get 2 values, 1 at launch, 1 at impact.
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PS  That's the equation of a projectile.
Bottle rockets have thrust --> a 3rd order equation, not a quadratic.