# Expressions - How to Add and Subtract Algebraic Expressions

## Equations- How it Works - Video

### Example 1

Example 1:

When adding/subtracting expressions, we need to find the like terms and combine them. It is easier to see what is happening if you reorganize the expression by putting the like terms closer together. In the expression, 4ab + 3ab + y the like terms are already next to each. So, the next step is to add the numbers in front of the like terms. In this case we 4ab + 3ab so we add the 4 and 3 to get 7. So the answer is 7ab + y.

### Example 2

Example 2:

When adding/subtracting expressions, we need to find the like terms and combine them. It is easier to see what is happening if you reorganize the expression by putting the like terms closer together. In the expression, 2ax - y + 3xa, we have two different like terms ax and y. Although the term ax is not written in 2ax and 3xa, they are the same because we can rearrange the letters from 3xa to 3ax because of the Commutative Property of Multiplication, which states AxB = BxA. So 5x2 = 2x5. After that we arrange the like terms together, and now we have 2ax + 3ax - y. Now we can add the numbers in front of the term ax. 2 plus 3 is 5. So the result is 5ax - y.

### Example 3

Example 3:

When adding/subtracting expressions, we need to find the like terms and combine them. It is easier to see what is happening if you reorganize the expression by putting the like terms closer together. In the expression, 2xy^2 + y + 3xy^2 + 6y, we have two different like terms xy^2 and y. So we can rearrange, the terms so the expression is 2xy^2 + 3xy^2 + y + 6y. Now we can add the numbers, (2 + 3 = 5), in front of the term xy^2. We can also add the numbers, (1 + 6 = 7), in front of the term, y. The result is 5xy^2 +7y.

### Example 4

Example 4:

When adding/subtracting expressions, we need to find the like terms and combine them. It is easier to see what is happening if you reorganize the expression by putting the like terms closer together. In the expression, 2xy^2 - 3x^2y - 4xy^2 + 6x^2y, we have two different terms xy^2 and x^2y. Let's rearrange the terms so that the like terms are closer together. Now we have 2xy^2 - 4xy^2 - 3x^2y + 6x^2y. Now we can subtract the numbers, (2 - 3 = -2), in front of the term xy^2. We can also add the numbers, (-3 + 6 = 3), in front of the term, x^2y. The result is -2xy^2 +3x^2y.

## Live Worksheet

Here is the link if you prefer.