Question 1 of 5
A park fountain shoots water upward, and its height above the ground after seconds is modeled by , where is in feet. According to the model, what is the maximum height of the water above the ground?
Explanation
For a quadratic function in the form , the maximum value occurs at the vertex because the coefficient of is negative. Here, and , so the time when the water reaches its maximum height is
Then evaluate the height at :
So the maximum height is feet.
Concept summary
For a downward-opening quadratic model, the maximum value is the -value of the vertex. Find the vertex time with , then substitute back into the function.