College algebra word problem

Question

A ball is thrown in the air from the top of a building. Its height, in meters above ground, as a function of time, in seconds, is given by h(t) = −4.9t^² + 14t + 6.

 How long does it take to reach maximum height? (Round your answer to three decimal places.)

Answer 1

take the derivative and set equal to zero, then solve for t

h' = -9.8t +14 =0

t = 14/9.8 = 7/4.9 = about 1.429 seconds