应该是-2x²,不是-3x²
3x²-x=1
原式=9x^4-3x³+15x³-5x²+3x²-7x+2001
=3x²(3x²-1)+5x(3x²-1)+3x²-7x+2001
=3x²+5x+3x²-7x+2001
=6x²-2x+2001
=2(3x²-x)+2001
=2+2001
=2003
应该是-2x²,不是-3x²
3x²-x=1
原式=9x^4-3x³+15x³-5x²+3x²-7x+2001
=3x²(3x²-1)+5x(3x²-1)+3x²-7x+2001
=3x²+5x+3x²-7x+2001
=6x²-2x+2001
=2(3x²-x)+2001
=2+2001
=2003