(9x²-3xy+y²)(3x+y) =(9x²*3x-3xy*3x+y²*3x)+(9x²*y-3xy*y+y²*y)
(9x²-3xy+y²)(3x+y) =(3х)^3+у^3==27х^3+у^3
(9x²-3xy+y²)(3x+y) =(9x²*3x-3xy*3x+y²*3x)+(9x²*y-3xy*y+y²*y)
(9x²-3xy+y²)(3x+y) =(3х)^3+у^3==27х^3+у^3