So first you factor out a common factor from both numbers, so the most you can factor out is 9x^4 y^10, from there you find two numbers that equal 4 that are the same, so you get two and two, and using the difference of squares, you find two numbers that will equal to -9x^12 y^10, so you get 3x^6 y^5 and -3x^6 y^5.
