Question 1081081


{{{ 27(x+y)^3+8(2x-y)^3}}}

={{{ 27(x+y)(x+y)(x+y)+8(2x-y)(2x-y)(2x-y)}}}

={{{ 27(x^2+y^2+2xy)(x+y)+8(4x^2-4xy+y^2)(2x-y)}}}

={{{ 27(x^3 + 3x^2y + 3xy^2 + y^3)+8(8x^3-12x^2y +6xy^2-y^3)}}}

={{{ 27x^3 + 81x^2y + 81xy^2 + 27y^3+64x^3 - 96x^2y + 48xy^2 -8y^3}}}

={{{ 91x^3 - 15x^2y + 129xy^2 + 19y^3}}}