SOLUTION: Please help me A model rocket is launched with an initial upward velocity of 45 m/s. The rocket's height h (in meters) after t seconds is given by the following. h=45t-5t

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Question 1173070: Please help me
A model rocket is launched with an initial upward velocity of 45 m/s.
The rocket's height h (in meters) after t seconds is given by the following.
h=45t-5t^2
Find all values of t for which the rocket's height is 20 meters.
Round your answer(s) to the nearest hundredth.
Found 2 solutions by ewatrrr, greenestamps:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

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+=+%289+%2B-+sqrt%28+65%29%29%2F%282%29+

t = 8.53sec  0r t = .47sec   Using a quadratic formula & rounding to the nearest hundredth

Wish You the Best in your Studies.

Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


45t-5t%5E2=20
5t%5E2-45t%2B20+=+0
t%5E2-9t%2B4+=+0

The quadratic does not factor. Use the quadratic formula do get an exact answer in radical form, or a graphing calculator to get an approximate decimal answer.