Solve the problem.
-A ball is thrown vertically upward at an initial speed of $40 \mathrm{ft} / \mathrm{sec}$. Its height (in feet) after $t$ seconds is given by
$$h(t)=t(40-16 t)$$
After how many seconds does the ball reach its maximum height?
A) 1.25 seconds
B) 1.67 seconds
C) 2.5 seconds
D) 5 seconds

Question

Quizplus · Accepted Answer

The height function $h(t) = t(40 - 16t)$ is a quadratic function in the form of $h(t) = -16t^2 + 40t$. The maximum height is reached at the vertex of the parabola, which occurs at $t = -\frac{b}{2a}$. Here, $a = -16$ and $b = 40$, so $t = -\frac{40}{2(-16)} = 1.25$ seconds.

Solve the Problem 40ft/sec40 \mathrm{ft} / \mathrm{sec}40ft/sec Its Height (In Feet) After

Solve the Problem $40 \mathrm{ft} / \mathrm{sec}$ Its Height (In Feet) After