1. Combine Like Terms
I can simplify expressions with several variables by combining like terms.

2. Constant Vocabulary A number with nothing else attached to it.
Examples: 1, 2, 47, 925

3. Variable Vocabulary A letter that represents an unknown number.
Examples: a, b, x, y

4. Coefficient Vocabulary The number in front of the variable.
Examples: 3x is the coefficient
2x is the coefficient

5. Like Terms:
In an expression, like terms are the terms that have the same variables, raised to the same powers (same exponents).
Examples: 4x and -3x or 2y2 and –y2

6. Like terms because each term consists of a single variable, x, and a numeric coefficient:
2x, 45x, x, 0x, -26x, -x
Like terms because they are all constants:
15, -2, 27, 9043, 0.6
Like terms because they are all y² with a coefficient: 3y², y², -y², 26y²

7. What are unlike terms?
The following two terms both have a single variable, but the terms are not alike since different variables are used: 17x, 17z
Each y variable in the terms below has a different exponent, therefore these are unlike terms: 15y, 19y², 31y5
Although both terms below have an x variable, only one term has the y variable, thus these are not like terms either: 19x, 14xy

8. Combine Like Terms
I can simplify expressions with several variables by combining like terms.

9. Like Terms – same variable with same exponent
Key Skills
Like Terms – same variable with same exponent
Simplify
When combining like terms, only use the coefficients.
6x + 2x =
6x + 2x = 8x
Simplify
4x + 3y – 2x + 4y =
2x + 7y
Never, NEVER, combine x’s and y’s or constant terms with variable terms. 2x + 7y ≠ 9xy and 3a + 6 ≠ 9a.

10. 5 cats + 3 cats
8 cats

11. 5a + 3a 8a

12. 5 apples + 3 oranges
5 apples + 3 oranges

13. 5 cats + 3 dogs
5 cats + 3 dogs

14. You Try
3y x – y + 5x
x + x