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# Needs helpppp ! thank you

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A ball is thrown from a height of 15 m above the ground. The height (in metres) of the ball at time t seconds after is thrown is given by the function h(t) =-5t² +22t +15, where t ≥ 0

Determine the time that the ball hits the ground and its velocity when it hits the ground.

Feb 20, 2021

#1
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The ball hits the ground when the height is 0, so we are solving the equation $$-5t^2+22t+15=0.$$

Using the quadratic equation, we get $$t= -\frac{3}{5}, 5$$. Time can't be negative, so the ball hits the ground after seconds.

I am unsure about the second part, but I hope this gets you started.

Feb 20, 2021
#2
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sorry how did you calculus t=-3/5 and 5

Guest Feb 20, 2021