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 first reach a height of 12 m?
+51 If I am correct, h(t) = −t^2+ 8t + 10 so, the rock first reaches the height of 12m at 12 = −t^2+ 8t + 10 and by solving that quadratic we get,
\(T=4±\sqrt{14}\)
So, the rock first reaches the height of 12m at \(4-\sqrt{14}\) which is aprox 0.25834261 seconds.
