3x4−6x3+kx2−8x−123x^4-6x^3+kx^2-8x-123x4−6x3+kx2−8x−12 is divisible by x−3x-3x−3, so it is also divisible by A3x2−43x^2-43x2−4B3x2+43x^2+43x2+4C3x2+x3x^2+x3x2+xD3x2−x3x^2-x3x2−xE4x2+x4x^2+x4x2+xF4x2−x4x^2-x4x2−x