Does this look right? Cannonball question

[mathatesme]

Cannonball fired on 45 deg angle from horizontal. Initial position is origin. initial velocity 100sqrt(2) ft/sec. Trajectory is y=x-(x/25)^2 where y>=0.

How far till it hits the ground? 312.5

What's the max height? 156.25

Here is what I got m(a) = 2*-(1/625)a + 1 = 0 which = -(1/312)a + 312 = 0

-(1/625)*312.5^2+312.5 = 156.25

Do you agree?

 

[hypermorphism]

...
Trajectory is y=x-(x/25)^2 where y>=0.
...
Here is what I got m(a) = 2*-(1/625)a + 1 = 0 which = -(1/312)a + 312 = 0

-(1/625)*312.5^2+312.5 = 156.25

Do you agree?

Yep, I agree.

 

[Data]

Nope... his is right. He has the $25$ squared too~

 

[hypermorphism]

Nope... his is right. He has the $25$ squared too~

Argh, my brain just blurred over this one.

 

[Data]

I made that mistake too, for a second, and was about to post it when I noticed he was right