In this lesson we will discuss what like-terms are and how to correctly solve problems involving this topic. Like-terms are terms that have the same variable. These terms can be combined by adding or subtracting the coefficients.
Example: 2y + 6y = (2+6)y = 8y
In the example listed above both terms have the variable “y”. The coefficients 2 and 6 are added together to combine the terms.
Example 1: 5y + 2y – 3x – 4x
First, we should determine what terms can be combined. 5y and 2y can be combined because they have the same variable “y”. -3x and -4x can also be combined because they share x as a variable.
The final answer should be reported in expression form: 7y-7x
Example 2: -2y -3x +2x
Determine what terms can be combined and report the final answer:
-2y -x
Example 3: 2y -3(5y-2x)
Before we can determine what terms can be combined, we must conduct some mathematical manipulation (distribution) in order to clearly see what terms can be combined.
2y-3(5y-2x) = 2y – 15y + 6x
Now we can combine the two “y” variables and bring down the x term. The final answer should be reported as:
-13y + 6x
Example 4: 7(2m-2) + 2(m-5) =
First distribute and the combine like-terms:
7(2m-2) + 2(m-5) = 14m – 14 + 2m – 10
Combine like-terms:
14m – 14 + 2m – 10
The final answer should be reported as:
16m – 24
Example 5: 7a +3 (2-4a)
Distribute first:
7a + 3(2 – 4a) = 7a + 6 – 12a
Now combine like-terms:
7a + 6 – 12a
Report the final answer:
-5a + 6
Example 6: 7a – 2a
Combine like-terms and report the final answer:
5a
