SOLUTION: Please help. Word problems are the worst! A ball is thrown vertically upward at an initial speed of 64 ft/sec. Its height (in feet) after t seconds is given by h(t)=t(64-16t). Aft

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Question 151517: Please help. Word problems are the worst!
A ball is thrown vertically upward at an initial speed of 64 ft/sec. Its height (in feet) after t seconds is given by h(t)=t(64-16t). After how many seconds does the ball reach its maximum height?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
h%28t%29=t%2864-16t%29 Start with the given function.


h%28t%29=64t-16t%5E2 Distribute


h%28t%29=-16t%5E2%2B64t Rearrange the terms


To find the time it takes to reach the max height, use this formula: t=%28-b%29%2F%282a%29.


t=%28-b%29%2F%282a%29 Start with the given formula.


From h%28t%29=-16t%5E2%2B64t, we can see that a=-16, b=64, and c=0.


t=%28-%2864%29%29%2F%282%28-16%29%29 Plug in a=-16 and b=64.


t=%28-64%29%2F%28-32%29 Multiply 2 and -16 to get -32.


t=2 Divide.


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Answer:

So it takes 2 seconds for the ball to reach the max height.