Based on the given roots and their multiplicities, the function is made of the following factors:
f(x) = x (x + 3)^2 (x - 1) (x - 3)^2
The roots represent the point in the graph where they touch the x-axis. With the given condition that the function has a positive leading coefficient and is of even degree, the group of the function touches the x-axis at the roots and is curved upwards.
