A football is kicked into the air from an initial height of 4 feet. The height, in feet, of the football above the ground is given by ￼s (t)=-16^2+50t+4, where t is time, in seconds, and t>=0. At what time will the football be 25 feet above the ground?
0.5 seconds or 3.625 seconds
0.5 seconds or 2.625 seconds
To answer the question above, substitute the given value of height.
25 = -16x² + 50t + 4
Solving the following equation by the use of quadratic formula,
x = (-b +/- sqrt (b² - 4ac)) / 2a
Subsituting the known values of a, b, and c
x = (-50 +/- sqrt (50² - 4(-16)(-21)) / 2x-16
The values of x are 0.5 and 2.625. Therefore, the answer is the fourth choice.