SOLUTION: Benjamin threw a rock straight up from a cliff that was 48 ft above the water. If the height of the rock h, in feet, after t seconds is given by the equation h=-16t^2+52t+48, how l

Question 1034820: Benjamin threw a rock straight up from a cliff that was 48 ft above the water. If the height of the rock h, in feet, after t seconds is given by the equation h=-16t^2+52t+48, how long will it take for the rock to hit the water?
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
For h(t) = -16t^2 + 52t + 48, which is the height of the rock as a function of time, we want to know at what time the height equals zero. So we set it equal to zero and solve for t...
-16t^2 + 52t + 48 = 0 (now divide by -4)
4t^2 - 13t - 12 = 0
which is factorable into
(4t + 3)(t - 4) = 0
so that
t = 4 seconds
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