Question 1173070
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Hi, 
h=45t-5t^2
Find all values of t for which the rocket's height is 20 meters.
20 = 45t - 5t^2
5t^2 - 45t + 20 = 0
t^2 - 9t + 4 = 0
{{{t = (9 +- sqrt( 65))/(2) }}}
t = 8.53sec  0r t = .47sec   Using a quadratic formula & rounding to the nearest hundredth
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