An algebraic **expression** consists of **terms**, for instance 3y + 4x – 2y + 7x has four terms. If there are **like terms** in an algebraic expression, we should always simplify the expression by **collecting the like terms**.

Because multiplication is **commutative**, ab and ba mean exactly the same thing (which other arithmetical operation is commutative?)

**Example**

**Exercise**

Let’s complete exercise 2A below from page 27 of the textbook:

The answers are below: