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The height (in meters) of a shot cannonball follows a trajectory given by h(t)=-4.9t+14t-0.4 at time t (in seconds). For how many seconds is the height of the cannonball at least 6 meters?

 

So I'm guessing then the function would be something like

-49t+140t-4 is greater than or equal to 6. However, when I solved it, I got t is greater than or equal to 10/91. However, that's incorrect. Can someone help? 

 Oct 24, 2021
 #1
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The solution is t = 9/14.

 Oct 24, 2021
 #2
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I suspect the first term of h(t) should be -4.9t^2  not -4.9t.

 

Then by setting h(t) = 6 you have a quadratic equation which will give you two solutions for t; the difference between them being the length of time required.

 Oct 24, 2021
edited by Alan  Oct 24, 2021

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