Question

a kicker starts a football game by "kicking off". The quadratic function y = -10x^2 + 25x models football's height after x seconds. How long, in seconds, is the football in the air?​

Answer 1

Answer: 2.5 seconds

Explanation:

x refers to time. Since we want to know how long it is in the air, we need to find the time (x) for the ball to land on the ground (y = 0)

0 = -10x² + 25x

0 = -5x(2x - 5)

0 = -5x 0 = 2x - 5

`0 = x\qquad (5)/(2)=x`

x = 0 seconds is when the ball was kicked

x = 5/2 --> 2.5 seconds is when the ball landed on the ground