Write
The equation splits the analysis into two cases. If , the remaining equation is , giving the cuspidal cubic
It is irreducible because is irreducible in : as a quadratic in , it could factor only if were a square in .
If , the other equations become
Their solutions are , which already lies on , and the two points
Thus the irreducible components are
Equivalently, the radical ideal of the cusp with two isolated-point components is