### Home > A2C > Chapter 11 > Lesson 11.2.4 > Problem 11-94

11-94.

For an object shot into the air, its height in feet above the ground after

*t*seconds is given by the equation

*. Use this equation to answer the following questions.*

For what times is the object on the ground?

Substitute 0 for

*h*.80

*t*− 16*t*^{2}= 0It is on the ground at 0 and 5 seconds.

Factor the equation.

16

*t*(5 −*t*) = 0For what domain is this function reasonable?

When is the height positive?

D: 0 ≤

*t*≤ 5

How long did it take the object to hit the ground?

At what time will the object be on the ground, not including when it starts?

5 seconds

For what times is the height greater than

feet?

Substitute 64 for

*h*and solve for*t*.Factor the equation.

Simplify.

Solve for

*t*.Use these values to find height greater that 64 ft.