x=√2+1
原式=(x²-x-2)/(x²-2x+1)
=[ x(x-1)-2]/(x-1)²
=[(√2+1)(√2+1-1)-2]/(√2+1-1)²
=[(√2+1)×√2-2]/(√2²)
=(2+√2-2)/2
=√2/2