Given that a is a rational number, is there a minimum value of the algebraic formula | A-1 | + | A-2 |? If yes, try to find the minimum value; if not, please explain the reason

Given that a is a rational number, is there a minimum value of the algebraic formula | A-1 | + | A-2 |? If yes, try to find the minimum value; if not, please explain the reason

There is a minimum value. Reason: from the geometric meaning of absolute value, it is to find a point a on the number axis, so that the sum of the distances from it to the two points 1 and 2 is the minimum. Therefore, when 1 ≤ a ≤ 2, this formula has a minimum value, and the minimum value is 1