A circle with area A = is expanding with time. If dA/dt= 5 cm^2/s, what is dr/dt when r = 6? Show all work

The ball will hit the ground 4 seconds after being thrown.

Step-by-step explanation:

By definition, the ball hits the grounds when the height is zero.

Then, knowing that the Quadratic function that models that situation is:

You can make it equal to zero:

Now you can use the Quadratic formula:

In this case you can identify that:

Therefore, knowing these values, you can substitute them into the Quadratic formula and then evaluate, in order to find the solution:

Choose the positive solution.

Then, the ball will hit the ground 4 seconds after being thrown.