The solution proves that for any event A and B, there is A-B = A-AB = ABˇ.

This is a collection of knowledge.

Let X belong to A-B, then X belongs to A, but not to B.

Because X already belongs to A, it is of course equivalent to that X belongs to A, not to A/B (both events A and B occur and are marked as AB).

A-B=A-AB。

In addition, A-B certainly means that A happened and B didn't, so it is AB.

Form:

Connect equal formulas (or numbers expressed in letters) with "=".

Equations are divided into equations with unknowns and equations without unknowns.

For example:

X+1= 3-an equation with unknowns;

2+1= 3-an equation without unknowns.

It should be noted that some equations with unknowns have no solutions, but they still have no solutions, such as x+1= x-x.