1. Key Points (3-1) Add or Subtract to Solve Equations Introduction
Activity: Tug of War team balance (5 groups)
Key Points
* Goal : Isolate the variable
- When solving an equation, you find all values of the variable that make the equation true.
- Use inverse operation to undo operation performed on variable
- Perform the same operation on both sides of the equation.
Ex.] x – 2 = x + (–2) = (inverse or opposite operation)
x + 0 = x = 7 Check: x – 2 = – 2 = 5 Solution = 5 True x = 7

2. Ex.] x + 5 = 7 x + 5 = 7 – 5 – 5 x = 2 Check x + 5 = 7 2 + 5 = 7
= 7
7 = True, x = 2

3. +(－4) +(－4) (inverse or opposite operation) －12 = n
Example:
Solve －8 = n －(－4)
－8 = n + 4
+(－4) (－4) (inverse or opposite operation)
－12 = n
Check: (substitute into original equation)
－8 = n －(－4)
－8 = (－12) －(－4)
－8 = (－12) + 4
－8 = －8
In Class - Page 135 #7 – 10, 15
Homework – Page 135, 136 #19 – 53 Odd