已知(3X⒉-2X+1)(X+b)中不含项X⒉,求b的值
[3x^2-2x+1][x+b]
=3x^3-2x^2+x+3bx^2-2bx+b
=3x^3-[2-3b]x^2+x-2bx+b
2-3b=0
b=2/3