36x^4-17x^2y^2+2y^4
=36x^4-9x^2y^2-8x^2y^2+2y^4
=9x^2(4x^2-y^2)-2y^2(4x^2-y^2)
=(9x^2-2y^2)(4x^2-y^2)
=(9x^2-2y^2)(2x+y)(2x-y)(有理数范围内)
=(3x+根号2y)(3x-根号2y)(2x+y)(2x-y)(实数范围内)