a stone is thrown upward from a bridge. The stones height in feet s(t) above water t seconds after the stone is thrown: s(t) = -16t^2 + 64t + 80. At what time is the stone at the maximum height above the water?

Question

matt101 · Answer

Do you know how to find the derivative of this equation?

anonymous · Answer

no

anonymous · Answer

that is all the information that I have but there are 3 other questions for the problem. This is a "take home" study quiz and I am allowed to use any resources available. The other questions are: find the max height of the stone above the watter. Find how long it takes for the stone to hit the water, rounded to 4 decimals. AND How tall is the bridge from the water

matt101 · Answer

Ok. In that case you need to complete the square for this equation so that you can determine the vertex of the parabola.

Since the equation is plotting position (with respect to time), the vertex of your parabola will be the maximum position reached. The time at that position will be the the value of t.

Do you remember how to complete the square?