Question

An object is launched directly upward from ground level at a rate of 96 feet per second. The height of the object is given by the equation y = −16x^2 + 96x.

When is the object AT OR ABOVE a height of 128 feet?

A) 1 ≤ x ≤ 3
B) 1 ≤ x ≤ 4
C) 2 ≤ x ≤ 3
D) 2 ≤ x ≤ 4

Answer 1

D

Explanation:

The x in the spot (x,y) is the time, while the y is how high the object is at.

The length of the time when the object is at or above 128 feet starts at exactly 2 seconds and ends at exactly 4 seconds.