an arrow is shot into the air is 144t-4.9t^2 meters above the ground t seconds after it released. During what periods of time is the arrow above 68.6 meters? round your answer to the nearest .01 second

Question

an arrow is shot into the air is 144t-4.9t^2 meters above the ground t seconds after it released. During what periods of time is the arrow  above 68.6 meters? round your answer to the nearest .01 second

mathmale · Answer

We'll need to solve the following inequality:$$144t-4.9t ^{2}>68.6.$$
It's easiest to solve the quadratic equation $$144t-4.9t ^{2}-68.8=0$$
first.
Mind giving that a try?  Then try answering the orginal question.

anonymous · Answer

ok

anonymous · Answer

1 sec

anonymous · Answer

ok i got it its 0.48 < t < 28.90

anonymous · Answer

i am correct hopefully?

mathmale · Answer

You're fast!  Would you mind checking your results?  In other words, determine whether your 0.48 and 28.90 are indeed solutions of that quadratic equation.  If they are, then you're right!

anonymous · Answer

ok 2 secs this time

mathmale · Answer

Wow.  "1 sec" to solve the problem, "2 secs" to check the results.  :)

anonymous · Answer

ok my results came up satisfactory! thanks to you mate

anonymous · Answer

and i wish i had your brain dude i swear i would of never known how to set up that equation
thanks alot mate

mathmale · Answer

My great pleasure!!!