If A2 − 2A + 1 = 1-A, then the value range of a is______ .

If A2 − 2A + 1 = 1-A, then the value range of a is______ .

∵ A2 − 2A + 1 = (a − 1) 2 = | A-1 | = 1-A, ∵ A-1 ≤ 0, ∵ a ≤ 1