Final answer:
The complete piecewise-defined function is necessary to determine f(0) - f(2). The question does not provide sufficient information to calculate the value.
Step-by-step explanation:
The student asked for the value of a piecewise-defined function at f(0) - f(2). However, the function itself was not fully provided in the question, and only partial information about a piecewise function is given. To calculate the value of the function at these points, we would typically substitute the x-values into the corresponding parts of the function definition, but without the complete function, we cannot do this accurately.