The quadratic function is .

For this function a = , so the graph opens down and the function has a maximum value

The maximum value of the function is the y-coordinate of the vertex.

The - coordinate of the vertex is .

    (Substitute the values a = and b = 28)

             (simplify)

The y-coordinate of the vertex by evaluating the function for = 0.777 .

                     (Original function)

       ( = 0.777)

.

The maximum value of the function is .

The function has maximum value.

The maximum value of the function is .