A ball is thrown vertically upward. After t seconds, its height h (in feet) is given by the function h(t)=68t-16t^2. What is the maximum height that the ball will reach?
Do not round your answer.

Question

A ball is thrown vertically upward. After t seconds, its height h (in feet) is given by the function h(t)=68t-16t^2. What is the maximum height that the ball will reach?
Do not round your answer.

anonymous · Answer

@tkhunny @jim_thompson5910

tkhunny · Answer

What do you know of "-b/(2a)"?

anonymous · Answer

absolutely nothing @tkhunny

tkhunny · Answer

That's annoying.  You should have that information before being given such a problem.

Okay, how about the Vertex Form of a parabola?

anonymous · Answer

y=a(x-h)^2+k, where (h,k) is the vertex.

anonymous · Answer

@tkhunny

tkhunny · Answer

That's the spirit.  Can you get your equation to look like that by Completing the Square?

anonymous · Answer

I'm not sure how @tkhunny

anonymous · Answer

I know the vertex is (2.125, 72.25)

tkhunny · Answer

Also annoying.  Why do they give you these problems and no tools to solve them?

How did you find that Vertex?

anonymous · Answer

I plotted it into my graphing calculator.

tkhunny · Answer

Well, we would have gotten to that method, eventually.  We are done.

What is the maximum height?  That second value fo the vertex.  Done.  Good work.