Question 1183267

Hi can you please help me with this question. A golf ball is hit from the top of a tee. The quadratic equation y=-5x^2 + 20x + 0.05 describes its height,y, in metres as time,x, in seconds passes. Determine how long the ball is in the air. Thanks for the help
<pre>Since time is x, the ball will be on the ground when y, or height = 0
Therefore, all you need to do is solve the quadratic. 
Using the quadratic equation formula, we get 2 solutions, as expected. They are: - .0025 and <font color = red><b><font size = 4>4.0025 seconds</font></font></b>.
Obviously, time, in this case, CANNOT be < 0 (negative), so time the ball was in the air is the LATTER.