A ball is thrown up at the edge of a 364 foot cliff. The ball is thrown up with an initial velocity of 72 feet per second.

Question

Its height measured in feet is given in terms of time t, measured in seconds by the equation h=−16t2+72t+364.

How high will the ball go?

To get how high the ball will go, am I supposed to factor −16t2+72t+364 or something?

Answer 1

Sorry, the equation is −16t^2+72t+364

Answer 2

nah. just recognize it's a parabola. Find the vertex. That will tell you how long it takes to get to its highest altitude. Then plug that value in for t in h(t) as given.

Finding the vertex of a parabola is easy, right. Algebra I.

Answer 3

oh ok. But if I wanted to find how long it takes the ball to come back to the ground then I would have to factor it right?

Answer 4

well, you could, or just use the Quadratic Formula. If you want to factor it, then we have

-16t^2+72t+364
-4(4t^2-18t-91)
Hmmm. Better stick with the QF.

Answer 5

thanks