A ball is kicked from ground level into the air. Its height y, in feet, after x seconds can be represented by the equation y = 40x -16x^2. What is the total elapsed time, in seconds, from the time the ball is kicked until it reaches grond level again?

Question

A ball is kicked from ground level into the air.  Its height y, in feet, after x seconds can be represented by the equation y = 40x -16x^2.  What is the total elapsed time, in seconds, from the time the ball is kicked until it reaches grond level again?

Is the answer - 25 s

bobpursley · Accepted Answer

ground level is y=0 0=40x-16x^2= x(40-16x) x=0, x= 40/16=2.5seconds