解方程：2x^2+2/x^2-7x+7/x+2=0

2(x²-2+1/x²)-7(x-1/x)+6=0
2(x-1/x)²-7(x-1/x)+6=0
[2(x-1/x)-3](x-1/x-2)=0
2(x-1/x)-3=0 x-1/x-2=0
2x²-3x-2=0 x²-2x-1=0
(2x+1)(x-2)=0 (x-1)²=2
x=-1/2 x=2 x=1+√2 x=1-√2
检验：