A polynomial minus x3-2y3 equals X3 + Y3, then the polynomial is___ .

A polynomial minus x3-2y3 equals X3 + Y3, then the polynomial is___ .

According to the meaning of the question: (x3-2y3) + (X3 + Y3) = x3-2y3 + X3 + Y3 = 2x3-y3