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The object hits the ground 8 seconds after launch.

Step-by-step explanation:

Let , where is the height of the object above the ground, measured in feet, and is time, measured in seconds. We notice that given expression is a second-order polynomial and hence, there are two roots, one of them corresponding to the instant when the object hits the ground. If , we get the following expression:

(Eq. 1)

Roots are found by applying the Quadratic Formula:

or

Only the first root offer a solution that is physically reasonable. Thus, the object hits the ground 8 seconds after launch.