Упростите вырожение (3x-y)(9x^2+y^2)(3x+y)-81x^4

Question

Упростите вырожение (3x-y)(9x^2+y^2)(3x+y)-81x^4

Answer 1

(3x-y)(9x²+y²)(3x+y)-81x⁴=
=[(3x-y)(3x+y)](9x²+y²)-81x⁴=
=(9x²-y²)(9x²+y²)-81x⁴=
=81x⁴-y⁴-81x⁴=-y⁴

Answer 2

(3x-y)(3x+y)(9x^2+y^2)-81x^4
(9x^2+3xy-3xy-y^2)(9x^2+y^2)-81x^4
(9x^2-y^2)(9x^2+y^2)-81x^4
81x^4+9x^2y^2-9x^2y^2-y^4-81x^4
-y^4