3×(2-x)²-(2x²+x-5)×(x-2)+(x⁴+4)×(4-x²)

3×(2-x)²-(2x²+x-5)×(x-2)+(x⁴+4)×(4-x²) = 3*(4 - 4x + x^2) - (2x^3 - 4x^2 + x^2 - 2x - 5x + 10) + (4x^4 - x^6 + 16 - 4x^2) = 12 - 12x + 3x^2 - 2x^3 + 4x^2 - x^2 + 2x + 5x - 10 + 4x^4 - x^6 + 16 - 4x^2 = -x^6 + 4x^4 - 2x^3 + 2x^2 - 5x +18