algebra
posted by Coach .
When a ball is thrown in the air, the height h of a ball in feet t seconds after the ball is thrown in the air, is given by the equation height = 25t–16t²
Use the quadratic equation to determine how many seconds goes by before the ball hits the ground?

when it hits the ground, height = 0
16t^2 25t=0
t(1625) = 0
t = 0 , (at the beginning of the throw,
or
t = 25/16 seconds
btw, if the quadratic equation ax^2 + bx + c = 0 has c = 0
then there is no need to use the formula, because it will always factor into x(ax + b) = 0