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A projectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. After how many seconds does the projectile take to reach its maximum height? Show your work for full credit.

Question

help! I'll fan and medal 
A projectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. After how many seconds does the projectile take to reach its maximum height? Show your work for full credit.

babtaooche · Answer

@agent0smith

agent0smith · Answer

Use -b/(2a)

b is the t coefficient. 

a is the t^2 coefficient.

babtaooche · Answer

Thank you

babtaooche · Answer

-704/16^2 like that? Or did I mix them up?

agent0smith · Answer

Look again: -b/(2a)

b is 704, yes.

a is not 16^2. a is -16

babtaooche · Answer

Oh okay, thank you so it would look like -704/-16?

babtaooche · Answer

Wait no I messed that up, hang on

babtaooche · Answer

-704/(2)(-16)?

agent0smith · Answer

Yeah but make sure you realize both the 2 and -16 are in the denominator

babtaooche · Answer

So how would tht look?

babtaooche · Answer

OH wait nevermind I got it

babtaooche · Answer

So then the final answer would be 22?

agent0smith · Answer

I'm assuming you can divide numbers correctly, so sure.

babtaooche · Answer

I'm just making sure, So when I put it in the equation 704 is negative, correct?

agent0smith · Answer

Not sure what you mean. All you do is plug things into -b/(2a)