1, both sides of the inequality are multiplied or divided by a negative number;

2. The reciprocal of the inequality with the same sign (that is, positive or negative) needs to be changed.

Both sides of inequality are multiplied or divided by a negative number;

For example:

5> 1 times a negative number-1 and becomes -5.

It is necessary to change the sign of the reciprocal of inequality with the same sign (i.e. the same positive or negative);

Example: 3; 1/8, this is because of the nature of the fraction. The larger the denominator, the smaller the fraction value.

Extended data:

Inequalities have three special properties:

1, inequality 1: Add (or subtract) the same number (or formula) on both sides of the inequality, and the direction of the inequality remains unchanged;

2. Inequality 2: Both sides of inequality multiply (or divide) the same positive number at the same time, and the direction of inequality remains unchanged;

3. Inequality 3: Both sides of inequality multiply (or divide) the same negative number at the same time, and the direction of inequality changes. ?

Summary: when the product of two positive numbers is constant, their sum has a minimum value; When the sum of two positive numbers is constant, their product has a maximum value.