1. Do these FAST! Solve for x. 1. x – 7 = 19 21 – x = 36 9x = 45 6x = 15
Answers:
x = 26
x = -15
x = 5
x = 5/2
x = 45

2. Multi-Step Equations
Coordinate
Algebra

3. Essential Question
How do I solve multi-step equations?

4. Multi-Step Equations
Equations that contain 2 or more different operations in order to solve the problem.
There will also be equations with variables on both sides.

5. Solve:
A.) 4x – 7 = 9
B.) -9x + 3 = 30
A.) x = 4
B.) x = -3

6. Solve:
C.)
D.)
C.) x = 20
D.) x = -80

7. Solve:
E.)
F.)
E.) x = 19
F.) x = -13

8. Tough one!
x =

9. Multi-step equations 5x – 7 = x + 3
Multi-step equations contain more than one of the same variable. Sometimes these variables are on opposite sides of the equal symbol.
ISOLATE your variable on one side of the equation.
5x – 7 = x + 3

10. Example 1 5x – 7 = x + 3 -x -x____ 4x – 7 = 3 +7 +7 4x = 10 4 4 x = 5
Step A:
Use Addition/Subtraction Properties of Equality to separate all variable terms from number terms on opposite sides of the equal symbol.
Step B:
Solve for x. ALWAYS reduce fractions!
Step C:
Check Solution.
5x – 7 = x + 3
-x -x____
4x – 7 =
4x =
x = 5 2

11. Variable terms already together
DO NOT use addition or subtraction property of equality. Simply combine like terms as they are, where they are!
2x + 3x = 25
5x = 25
x = 5

12. If you see Parentheses . . .
Then your 1st step will be to use the DISTRIBUTIVE PROPERTY
After ( )’s are gone, then follow steps A-C from example 1.

13. Example 2 2(2x + 3) = -4x + 6 4x + 6 = -4x + 6 +4x +4x___ 8x + 6 = 6
8x =
x = 0 (not 8 or undefined)

14. Example 3 -(3x + 5) = 5x + 1 -3x - 5 = 5x + 1 +3x +3x___ -5 = 8x + 1
= 8x
8 8
x = -3/4

15. Summarizer
What operation(s) do you start with when solving a multi-step equation?
Addition OR Subtraction!

16. HOMEWORK
worksheet