Question

A creature on the moon throws a rock off a cliff. The height of the rock above the surface of the moon, in meters, t seconds after it is thrown is given by h(t) = −t 2 + 8t + 10. When does the rock hit the surface of the moon?

Answer 1

9.099 seconds

Explanation:

The rock hits the surface of the moon when is t is 0.

`-t^2 + 8t + 10 = 0\\t^2 - 8t - 10 = 0`

Use the quadratic formula

t = -1.099 and 9.099

Since time can't be negative, the answer is t = 9.099