若3x²-x=1求6x³+7x²-5x+1994的值

6x³+7x²-5x+1994
=6x³-2x²-9x²-5x+1994
=2x(x²-x)-9x²-5x+1994
=2x-9x²-5x+1994
=-9x²-3x+1994
=-3(3x²-x)+1994
=-3x1+1994
=1994-3
=1991额我看的别人的说答案是1997啊哦，刚才写错符号了6x³+7x²-5x+1994=6x³-2x²+9x²-5x+1994=2x(x²-x)+9x²-5x+1994=2x+9x²-5x+1994=9x²-3x+1994=3(3x²-x)+1994=3x1+1994=3+1994=1997