(a²-b²)/a÷[(2ab-b²)/a-a]
=(a+b)(a-b)/a÷(2ab-b²-a²)/a
=(a+b)(a-b)/a·[-a/(a-b)²]
=-(a+b)/(a-b)
∵a=1+√2 b=1-√2
∴a+b=2a-b=2√2
∴原式=-2/2√2=-√2/2