原式=(3x²+3x-x²+x)/(x+1)(x-1)*x(x²-1)/x²(x²-4)
=(2x²+4x)/(x+1)(x-1)*(x+1)(x-1)/x(x+2)(x-2)
=2x(x+2)/(x+1)(x-1)*(x+1)(x-1)/x(x+2)(x-2)
=2/(x-2)
=2/(√2+2-2)
=2/√2
=√2