a^ - 2a = 3/2 a^-2a 1 = 5/2 (a-1)^ = 5/2
2b- b^ = 1 b^-2b 1 = -1 1=0 (b-1)^ = 0 b = 1
(a-b)(b-2) = 根号下(a-1) (-1) = 正负根号下5／2
其实可以解除ab代人计算啊