# What is a ? B?

**∆B**which is called the symmetric difference between A and

**B**is defined as (A-B)U(B-A). Now, A-B is the set of all elements which are in A but not in

**B**. So, A -

**B**= {1,2}. Similarly, B-A is the set of all elements which are in

**B**but not in A.

Hereof, what is a _firxam_#8710; B in sets?

usually denotes the operation of symmetric difference of two **sets**: if A and **B** are **sets**, A?**B**=(A∖**B**)∪(**B**∖A). In plain English, A?**B** is the **set** of things that belong to exactly one of A and **B**.

**B is the**symmetric difference of the sets A and

**B**, the set of elements that are in exactly one of A and

**B**. It is also equal to (A∪

**B**)∖(A∩

**B**).

Just so, what is a Delta B?

The **Delta B**, or Thor-**Delta B** was an American expendable launch system used for nine orbital launches between 1962 and 1964. The first stage was a Thor missile in the DM-21 configuration, and the second stage was the **Delta** D, which was derived from the earlier **Delta**.

In mathematics, the **symmetric difference**, also known as the disjunctive union, of two sets is the **set** of elements which are in either of the sets and not in their intersection. The **symmetric difference** of the sets A and **B** is commonly denoted by. or. or. For example, the **symmetric difference** of the sets and is .