-1/9x²-1/6x-1 =-(1/9x²+1/6x+1)=-(1/3x+1)^2不对吧不好意思，算错了-1/9x²-1/6x-1 =-1/18(2x²+3x+1)=-1/18(2x+1)(x+1)1/18(2x²+3x+1)中的1不对吧去括号后为-1/9x²-1/6x-1/18-1/9x²-1/6x-1 =-(1/9x²+1/6x+1)=-(1/3x+1/4)^2-15/16 =[i*（根号15）/4]^2-(1/3x+1/4)^2=(i*（根号15）/4-1/3x-1/4)(i*（根号15）/4+1/3x+1/4)只能这么分解了