x+1/x除以（x- 1+x²/2x）
=(x+1)/x÷(2x^2-1-x^2)/2x
=2(x+1)/(x^2-1)
=2(x+1)/(x+1)(x-1)
=2/(x-1)
已知x=√2+1 x-1=√2
代入得原式=2/√2=√2