Question

已知x=根号2,求代数式(x^2-2x+1)/(x^2-1)/[1-3/(x+1)]的值。急急急！！

2012年庆阳的一道中考题，我最后算的是-（根号2）/2

Answer 1

原式=(x-1)²/(x+1)(x-1)/[(x+1-3)/(x+1)]
=(x-1)/(x+1)*(x+1)/(x-2)
=(x-1)/(x-2)
=(√2-1)/(√2-2)
=(√2-1)(√2+2)/(2-4)
=-√2/2