1 . a & gt； B, then a+c > b+c

2.a>b, c>0, then ac> BC.

3.a>b, c<0, and then AC.

In addition, inequalities also include reflexivity and transitivity. The same inequality can be added and the same non-negative inequality can be multiplied.

The essence of inequality is:

1, add (or subtract) the same number (or algebraic expression) on both sides of the inequality, and the direction of the inequality remains unchanged;

2. Both sides of the inequality are multiplied (or divided) by the same positive number, and the direction of the inequality number remains unchanged;

3. When both sides of inequality are multiplied (or divided) by the same negative number, the direction of inequality sign changes.