Answer:
The axis of symmetry of the parabola is the vertical line passing through the vertex, which is x = 3.5. Since the parabola is symmetric about this line, its roots (or zeros) must be equidistant from the axis of symmetry.
The distance between the axis of symmetry x = 3.5 and the point (0, 3) is 3.5, so the distance between the axis of symmetry and the other x-intercept must also be 3.5. This other x-intercept is (6, 0), so the distance between x = 3.5 and x = 6 is 2.5.
Therefore, the roots of the polynomial function are x = 3.5 - 2.5 = 1 and x = 3.5 + 2.5 = 6, which means that the factors of the polynomial are (x - 1) and (x - 6).
So, the answer is x - 1 or (x - 1)