Posted by **manda** on Wednesday, October 2, 2013 at 11:50am.

A cannonball is fired across a field. Its height above the ground after t seconds is given by -16t^2+104. How long does it take for the ball to reach its maximum height of 169 feet?

- math -
**Reiny**, Wednesday, October 2, 2013 at 12:23pm
169 = -16t^2 + 104

16t^2 = -65

no solution,

it will never reach 169 ft, the maximum height is 104 ft when t = appr 2.5 seconds

- math -
**Bosnian**, Wednesday, October 2, 2013 at 12:38pm
If -16t^2+104 mean :

- 16 t ^ 2 + 104 t

then :

in google type :

quadratic equation online

Wfen you see list of results click on :

Free Online Quadratic Equation Solver: Solve by Quadratic Formula

Select one of method.

Then in rectangle type :

- 16 t ^ 2 + 104 t = 169

and click option : solve it !

You will see solutions step - by - step

In this case solution are :

t = 13 / 4 sec = 3.25 sec

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