A student kicks a ball during gym class The balls height in

A student kicks a ball during gym class. The ball\'s height in feet x seconds after being kicked is given by -16x^2+40x. When did the ball hit the ground?

Solution

Given Height = -16x^2+40x.

where x-time in seconds.

Need to find the time that when the ball hit the ground.

Ball is hitting the ground means height = 0

Height = -16x^2+40x.

0 = -16x^2+40x.

-16x^2+40x = 0

-8x(2x-5) = 0

-8x = 0 or 2x-5 = 0

x=0 2x = 5

x=5/2

x=2.5

X shouldn\'t be zero because ball takes some time to hit the ground.

Therefore , x = 2.5seconds.

The ball hit the ground in 2.5seconds.