Antoine stands on a balcony and throws a ball to his dog, who is at ground level.
The ball's height (in meters above the ground), xxx seconds after Antoine threw it, is modeled by:
h(x)=-2x^2+4x+16h(x)=−2x
2
+4x+16h, left parenthesis, x, right parenthesis, equals, minus, 2, x, squared, plus, 4, x, plus, 16
How many seconds after being thrown will the ball hit the ground?
seconds

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.

i leave the calculator work to you.

7. diameter 4 miles, circumference 4π miles

8. radius 0.2 miles, circumference 0.4π miles

[this is a bad problem because the actual radius of a car on the track is less than 0.2 miles so the answer is less than 0.4π miles]

9. radius 6 feet, circumference 12π feet

10. diameter 14 cm, circumference 14π cm

11. diameter 4.8 feet, circumference 4.8π feet