1. Like Terms

2. Like Terms
A variable is a letter that represents an unknown number. The variable is always preceded by a number (called a coefficient). If no number appears, the coefficient is 1. For example…
x The coefficient is 1.
-x The coefficient is -1.
2x The coefficient is 2.
-3x The coefficient is -3.
and so on…

3. Combining Like Terms
A term is any number or expression of a number in mathematic, such as integers, variables, fractions, decimals, anything…
You can multiply and divide different terms to one another. For example…
2 · y = 2y
a · b = ab
a · a = a2
3a · 2b = 6ab

4. Combining Like Terms
However, you CANNOT add and subtract different terms to one another. For example…
2 + a = 2 + a Cannot add unlike terms.
2a + a = 3a Can add like terms.
3a2 + a = 3a2 + a Cannot add unlike terms.
3a2 + a2 = 4a2 Can add like terms.

5. Practice
Match the like terms, then add and subtract them. 3 -2x 7x 2a2 2xy -3a 3z 8z 4a x2y 5a2 -4 5x3 -xy2 11xy2 -3x3 xyz 4xy 10x2y -xyz