9x^4+12x^3-3x^2-7x+2003
=9x^4-3x^2+12x^3-7x+2003
=3x（3x^3-x）+12x^3-7x+2003
=3x+12x^3-7x+2003
=12x^3-4x+2003
=4(3x^3-x）+2003
=2007