3.2 Solving Equations by Using Addition and Subtraction

1
3.2 Solving Equations by Using Addition and
Subtraction

• Addition Property of Equality
• If the same number is added to each side of an
  equation, the resulting equation is true.
• For any numbers a, b, and c, if a b, then a c
  b c.
• If the same number is added to each side of an
  equation, then the result is an equivalent
  equation. Equivalent equations have the same
  solution.

2
Solve by Adding a Positive Number

• Solve m 48 29. Then check your solution.
• m 48 29
• m 48 48 29 48
• m 77
• Check
• m 48 29
• 77 48 29
• 29 29
• The solution is 77.

3
Solve by Adding a Negative Number

• Solve 21 q -18. Then check your solution.
• 21 q -18
• 21 q (-21) -18 (-21)
• q -39
• Check
• 21 q -18
• 21 (-39) -18
• -18 -18
• The solution is -39.

4
Subtraction Property of Equality

• If the same number is subtracted from each side
  of an equation, the resulting equation is true.
• For any numbers a, b, and c, if a b, then a c
  b c.

5
Solve by Subtracting

• Solve 142 d 97. Then check your solution.
• 142 d 97
• 142 d 142 97 142
• d - 45
• Check 142 d 97
• 142 (-45) 97
• 97 97
• The solution is -45.

6
Solve an Equation

• Solve

7
Write and Solve an Equation

• Write an equation for the problem. Then solve
  the equation and check your solution.
• A number increased by 5 is equal to 42. Find the
  number.
• n 5 42
• n 5 5 42 5
• n 37
• Check
• n 5 42
• 37 5 42
• 42 42
• The solution is 37.

8
More Practice!!!!!

• Homework Worksheet 3.2.