Multiply: (x+3)(x−3)(x2+9)(x + 3)(x - 3)(x^2 + 9)(x+3)(x−3)(x2+9).
x4−81x^4 - 81x4−81
x4+81x^4 + 81x4+81
x4−9x^4 - 9x4−9
x4−18x2+81x^4 - 18x^2 + 81x4−18x2+81