please help


A ball is thrown vertically upward. After t seconds, its height h (in feet) is given by the function h(t) = 112t -16t^2 . After how long will it reach its maximum height?

Do not round your answer.

Respuesta :

Answer: After [tex]3.5\ seconds[/tex]

Step-by-step explanation:

Knowing that after "t" seconds, its height "h" in feet is given by the function:

 [tex]h(t) = 112t -16t^2[/tex]

The maximum height is the y-coordinate of the vertex of the parabola. Then, we can use the following formula to find the corresponding value of "t" (which is the x-coordinate of the vertex):

[tex]t=\frac{-b}{2a}[/tex]

In this case:

[tex]a=-16\\b=112[/tex]

Substituting values, we get that the ball will reach the maximum height after:

[tex]t=\frac{-112}{2(-16)}\\\\t=3.5\ seconds[/tex]