Replace all "y" values in the piecewise function with "-y." If the value returned is the same in both cases, after the function is simplified, the axis of symmetry is the x - axis.
Replace all "x" values in the function with "-x." Simplify the function. If the function is the same after simplification, there exists symmetry about the y - axis.
Replace all "x" and "y" values with "-x" and "-y." If the piecewise function simplifies to a form identical to the starting function, it is symmetrical about the origin.