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?

Answer 1

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

Answer 2

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