(x-1)² -2(x-1) = - 1
(x-1)²-2(x-1)+1 = 0
(x-1-1)² = 0 用到 A²-2A + 1 = (A-1)²
x=2
(1+√2)x² = (1-√2)x x≠0时,两边同时约去 x
(1+√2)x=(1-√2)
x = (1 - √2)² 或者 x = 0