The roots of the function are approximately x=0 sec and x=9.8sec :. The first root tells us that the height of the arrow was meters above his bow after seconds right before Andrew first shot it which makes sense. The second root says that it takes approximately seconds for the arrow to return to the height of the bow. Remember that we already calculated our vertex, so we don't need to inspect our graph to find it, but we can use it to confirm it. We can interpret our vertex to mean that at approximately seconds, the arrow reached a maximum/minimum height of meters.