posted by Jane on .
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 ground level again?
I used the quadratic formula and got 2.5. Is this correct?
if you did ...
40x - 16x^2 = 0
x(40 - 16x) = 0
x = 0 or x = 40/16 = 2.5
then you are correct
the x = 0 , represents the time it was kicked