giving out medals!!!
A projectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = - 16t2 + 576t. After how many seconds does the projectile take to reach its maximum height? Show your work for full credit.

Question

giving out medals!!!
A projectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = - 16t2 + 576t. After how many seconds does the projectile take to reach its maximum height? Show your work for full credit.

anonymous · Answer

h(t) = -16t^2 + 640t
This is a "quadratic" (think parabola) and because the coefficient associated with the t^2 term is NEGATIVE, we know it opens downward.
Therefore, the vertex is the maximum.

 
.
The time (secs) when it reaches the max is:
t = -b/(2a)
t = -640/(2(-16))
t = -640/(-32)
t = 20 seconds

anonymous · Answer

this is just an example do the same thing with ur problem

anonymous · Answer

medal, hello where is it

mayaal · Answer

thankyou,but are we are looking for the vertex,aren't we?

anonymous · Answer

yes yes see if this link helps http://www.algebra.com/algebra/homework/quadratic/Quadratic_Equations.faq.question.644714.html

mayaal · Answer

oh I got it.thankyou again:)

anonymous · Answer

welcome:)