已知:x=根号2-1分之3,求x+2分之x^2-x-6

已知:x=根号2-1分之3x=3(√2+1)/(√2-1)(√2+1)x=3√2+3x+2分之x^2-x-6=（x-3)(x+2)/(x-2)=（3√2+3-3)(3√2+3+2)/(3√2+3-2)=（3√2)(3√2+5)/(3√2+1)=（3√2)(3√2+5)(3√2-1)/(3√2+1)(3√2-1)=（18+15√2)(3√2-1)/(18-1)=（54√2-18+90-15√2)/(18-1)=（39√2+72)/17