已知X的平方减2X等于2,将下列先化简,再求值.

(x-1)^2+(x+3)(x-3)+(x-3)(x-1)
=x^2-2x+1+x^2-9+x^2-4x+3
=3x^2-6x-5
=3(x^2-2x)-5 把x^2-2x=2代人
=3*2-5
=1