Equations and Expressions—Combing Like Terms
Equations (“work on both sides of an = sign”)
• No matter how many steps…
o GOAL of Equations: isolate the variable; (“solve for x”)
o LAW of Equations: what you do to one side (inverse operation), you do to
the other
Expressions
• Work on only one side: a+b
13x =
4-5-y
Combining Like Terms
(Pssst! You HAVE a NOTES SHEET on this from class! It’s green!)
• Remember the PARTS of an equation—the “TERMS”
o Terms include:
 Numbers by themselves
 Numbers smooshed to variables
 Variables (letters)
o -2y – 4 + 5b = 16 - c
 Terms: -2y, -4, 5b, 16, -c
 Variables: y, b, -c
Simplifying like terms:
 Coefficients: -2, 5
10x and 3x = 13x
-18 and 3 = -15
• Simplifying expressions or solving equations
1
4a and 𝑎𝑎 = 4.5a
o Combine like terms!
2
o “LIKE TERMS” mean they look alike
 Same variable AND same exponent
o Just follow your integer rules for adding and subtracting—watch out for
negatives!
Like Terms
10x and 3x
1
4a and 𝑎𝑎
2
18 and -4
-2rs and 30sr
-2rs and 30sr—SAME variable &
exponent
NOT like terms
3y2 and 6y:
same variable, different exponent
2a3 and 2b3:
same exponent, different variable