Let me explain something to you. According to that coordinate, we can see that B is negative on the left of 0, a c is positive, and the absolute values are all integers, so |a|=a, |b|=-b, |c|=c The absolute value of a positive number is itself, and the absolute value of a negative number is its inverse. So there are A/| A | = A/A = 1, B/| B | = B/-B =- 1, C/| C | = C/C = 1.