(1/x+1/x+3)×2+x-2/x+3=1
两边乘以x(x+3)
2(x+3+x)+x(x-2)=x(x+3)
4x+6+x^2-2x=x^2+3x
x=6
[验证]
2*(1/6+1/9)+4/9
=2*5/18+8/18=1