(3x+2)(3x-2)-5x(3x-2)+(2-3x)²
=9x²-4-15x²+10x+9x²-12x+4
=3x²-2x
=3x(-1/6)²+2x1/6
=1/12+1/3
=5/12
如果本题有什么不明白可以追问,