(9+4根号2）x^2-(1+2根号2)x-2=0
[(1+2根号2)x]^2-(1+2根号2)x-2=0
[(1+2根号2)x+1][(1+2根号2)x-2]=0
(1+2根号2)x=-1
x=-1/(1+2根号2)=-(2根号2-1)/7
或
(1+2根号2)x=2
x=2/(1+2根号2)=2(2根号2-1)/7太给力了，你的回答已经完美的解决了我问题！