A projectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t^2 + 640t. After how many seconds does the projectile take to reach its maximum height? Show your work for full credit.

You can find the answer by using the formula x=-b/2a

Step-by-step explanation:

Remember the maximum height will be at the vertex. The x value of the vertex is your time, so use x=-b/2a. Then if it had also asked what the height was, you would plug that answer into your equation to find the y value of the vertex. Pretty sure your teacher is just asking you to find the x though:)