Solve the problem
-April shoots an arrow upward into the air at a speed of 64 feet per second from a platform that is 21 feet high. The height of the arrow is given by the function $h ( t ) = - 16 t ^ { 2 } + 64 t + 21$, where $t$ is the time is seconds. What is the maximum height of the arrow?
A) $85 \mathrm { ft }$
B) $21 \mathrm { ft }$
C) $17 \mathrm { ft }$
D) $64 \mathrm { ft }$

Question

Quizplus · Accepted Answer

The maximum height of the arrow can be found by using the vertex formula for a quadratic equation $h(t) = -16t^2 + 64t + 21$. The vertex formula $t = -\frac{b}{2a}$ gives the time at which the maximum height is reached. Here, $a = -16$ and $b = 64$, so $t = -\frac{64}{2(-16)} = 2$. Plugging $t = 2$ back into the equation gives $h(2) = -16(2)^2 + 64(2) + 21 = 85$. Therefore, the maximum height is 85 ft.

Solve the Problem -April Shoots an Arrow Upward into the Air

Solve the Problem
-April Shoots an Arrow Upward into the Air