1. Lesson 2.2: Solving Equations Using Addition and Subtraction Algebra 1 CP Mrs. Mongold

2. Solving an equation To solve an equation means to find all values of the variable that make it true

3. Solving an equation To solve an equation means to find all values of the variable that make it true Steps to solve an equation:

4. Solving an equation To solve an equation means to find all values of the variable that make it true Steps to solve an equation: ◦ 1. Get the variable on one side of the equation and get the numbers on the other side

5. Solving an equation To solve an equation means to find all values of the variable that make it true Steps to solve an equation: ◦ 1. Get the variable on one side of the equation and get the numbers on the other side ◦ 2. Check your answer in the original equation to make sure it makes sense

6. Addition Property of Equality: ◦ If you add the same amount to each side of the equal sign, the equation is true

7. Addition Property of Equality: ◦ If you add the same amount to each side of the equal sign, the equation is true  Think to yourself to “undo” subtraction you do it’s opposite which is addition

8. Addition Property of Equality: ◦ If you add the same amount to each side of the equal sign, the equation is true  Think to yourself to “undo” subtraction you do it’s opposite which is addition Ex: m – 48 = 29

9. Subtraction Property of Equality: ◦ If you subtract the same amount from each side, the equation is true

10. Subtraction Property of Equality: ◦ If you subtract the same amount from each side, the equation is true  Think to yourself to “undo” addition you do the opposite which is subtraction

11. Subtraction Property of Equality: ◦ If you subtract the same amount from each side, the equation is true  Think to yourself to “undo” addition you do the opposite which is subtraction Example: 42 + d = 27

12. Your turn Solve each equation 1. x+5 = 7

13. Your turn Solve each equation 1. x+5 = 7

14. Your turn Solve each equation 1.x+5 = 7 -5 -5

15. Your turn Solve each equation 1.x+5 = 7 -5 -5 x = 2

16. Your turn Solve each equation 1.x+5 = 7 -5 -5 x = 2 CHECK: 2 + 5 = 7

17. Your turn Solve each equation 2. x + 3 = -4

18. Your turn Solve each equation 2. x + 3 = -4

19. Your turn Solve each equation 2. x + 3 = -4 -3 -3

20. Your turn Solve each equation 2. x + 3 = -4 -3 -3 x = -7

21. Your turn Solve each equation 2. x + 3 = -4 -3 -3 x = -7 CHECK: - 7 + 3 = - 4

22. Your turn Solve each equation 3. x + 7 = 2

23. Your turn Solve each equation 3. x + 7 = 2 How do I “undo” addition?

24. Your turn Solve each equation 3.x + 7 = 2 -7 -7 How do I “undo” addition?

25. Your turn Solve each equation 3.x + 7 = 2 -7 -7 x = -5 How do I “undo” addition?

26. Your turn Solve each equation 3.x + 7 = 2 -7 -7 x = -5 CHECK: - 5 + 7 = 2 How do I “undo” addition?

27. Your turn Solve each equation 4. 32 = r – 8

28. Your turn Solve each equation 4. 32 = r – 8 How do I “undo” subtraction?

29. Your turn Solve each equation 4. 32 = r – 8 +8 = + 8 How do I “undo” subtraction?

30. Your turn Solve each equation 4. 32 = r – 8 +8 = + 8 40 = r How do I “undo” subtraction?

31. Your turn Solve each equation 4. 32 = r – 8 +8 = + 8 40 = r CHECK: 32 = 40 - 8 How do I “undo” subtraction?

32. Your turn Solve each equation 5. 7 = 42 + t

33. Your turn Solve each equation 5. 7 = 42 + t How do I move the 42? Is it being added or subtracted or something else?

34. Your turn Solve each equation 5. 7 = 42 + t It’s positive so it’s like adding…. To “undo” addition we will subtract!!

35. Your turn Solve each equation 5. 7 = 42 + t -42 -42 It’s positive so it’s like adding…. To “undo” addition we will subtract!!

36. Your turn Solve each equation 5. 7 = 42 + t -42 -42 -35 = t It’s positive so it’s like adding…. To “undo” addition we will subtract!!

37. Your turn Solve each equation 5. 7 = 42 + t -42 -42 -35 = t t = -35 It’s positive so it’s like adding…. To “undo” addition we will subtract!! What property is this?

38. Your turn Solve each equation 5. 7 = 42 + t -42 -42 -35 = t t = -35 It’s positive so it’s like adding…. To “undo” addition we will subtract!! What property is this? - Symmetric

39. Your turn Solve each equation 5. 7 = 42 + t -42 -42 -35 = t t = -35 CHECK: 7 = 42 + (- 35) It’s positive so it’s like adding…. To “undo” addition we will subtract!! What property is this? - Symmetric

40. Your turn Solve each equation 6. h – 12 = -27

41. Your turn Solve each equation 6. h – 12 = -27 How do I “undo” subtraction?

42. Your turn Solve each equation 6. h – 12 = -27 +12 +12 How do I “undo” subtraction?

43. Your turn Solve each equation 6. h – 12 = -27 +12 +12 h = -15 How do I “undo” subtraction?

44. Your turn Solve each equation 6. h – 12 = -27 +12 +12 h = -15 CHECK: -15 -12 = -27 How do I “undo” subtraction?

45. Your turn Solve each equation 7.

46. Your turn Solve each equation 7. How do I “undo” subtraction?

47. Your turn How do I “undo” subtraction?

48. Your turn How do I “undo” subtraction? Oh no! A fraction…. Are we scared?

49. Your turn How do I “undo” subtraction? Oh no! A fraction…. Are we scared? NO… fractions aren’t scary, like denominators Make this one easy to solve

50. Your turn How do I “undo” subtraction? Oh no! A fraction…. Are we scared? NO… fractions aren’t scary, like denominators Make this one easy to solve

51. Your turn How do I “undo” subtraction? Oh no! A fraction…. Are we scared? NO… fractions aren’t scary, like denominators Make this one easy to solve

52. Your turn How do I “undo” subtraction? Oh no! A fraction…. Are we scared? NO… fractions aren’t scary, like denominators Make this one easy to solve CHECK:

53. Homework Page 15