已知:x=根号2-1分之3,求x+2分之x^2-x-6
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已知:x=根号2-1分之3
x=3(√2+1)/(√2-1)(√2+1)
x=3√2+3
x+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
x=3(√2+1)/(√2-1)(√2+1)
x=3√2+3
x+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
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