2. Learn to identify and evaluate expressions.

3. WARM-UP Please answer the questions below showing all your work! 1.563 + 981 = 2.298 – 189 = 3.46 x 847= 4.2952 ÷ 24 = 1,044 109 38,962 123

5. Order of Operations - Warm Up Simplify. 1. 4 + 8  2  15 2. 87  10  5 x 3 3. 6(5 + 2) + 2 4. 35  7  5 + 2 5 81 44 27

6. Do you want to see something VERY scary!

7. Vocabulary variable constant algebraic expression

8. Equation A mathematical statement showing two expressions are indeed, equal.

9. 3 types of Equations #1. A true equation 3 + 5 = 8

10. 3 types of Equations #2. A false equation 3 + 5 = 6

11. 3 types of Equations #3. A conditional equation 3 + X = 8 We try to make these equations true!

12. SOLVE When you solve an equation or inequality you find the value(s) of the variable that makes the equation true.

13. SIMPLIFY This is exactly what it sounds like. It is expressing a mathematical statement in the “simplest” form possible.

14. When you were in second grade you did problems like this! 3 + 5 = You realized the box represented the unknown number!

15. When you were in Third grade you did problems like this! 3 + =8

16. When you were in Fourth Grade you did problems like this! ? + 5 =8 You realized the Question Mark was the same as the box!

17. When you were in Fifth Grade you did problems like this! n + 5 =8 Do you remember those “n”s? It meant the same as the box and the question mark!

18. Now, you are in Sixth Grade…. problems look like this! 3 + x =8 The X means the same as the, the “n”, the box and the question mark!

19. Scary!

20. Do you want to see something VARY scary!

22. Do you want to see something VARIABLE

23. VARIABLE A variable is a symbol, normally a letter of the alphabet, that represents one or more numerical values. It takes the place of a number!

24. The “X” is a variable! Remember….

25. VARIABLE A variable is a symbol, normally a letter of the alphabet, that represents one or more numerical values. It takes the place of a number!

26. Very Scary!

27. ALGEBRA

29. WARM-UP What is a variable? What is a constant? If X =4, then 5 + X = ?

30. We can use any letter we want as a variable except for one. Do you know which letter we should never use as a variable? 0 Because it looks like an “o” “oh”

31. Check these out! 5 + y = 8 r – 3 = 11 6 + 4 = k 8 x a = 16 These are all variables! These are easy equations to solve!

32. These are all conditional equations! 5 + y = 8 r – 3 = 11 6 + 4 = k 8 x a = 16 Remember, our goal is to make conditional equations into TRUE EQUATIONS!

33. Check these out! 5 + y = 8 y = 3 y – 3 = 11 y = 15 6 + 4 = y y = 10 8 x y = 16 y = 2 y is worth a different amount each time. It “varies”. That is why we call it a variable!

34. A variable is a letter or symbol that represents a quantity that can change. A constant is a quantity that does not change.

35. Constant or Variable? Your Weight! variable

36. Constant or Variable? # of days in a week constant

37. Algebraic Expressions NOT Algebraic Expressions 150 + y 85 ÷ 5 35  w + z 10 + 3  5 To evaluate an algebraic expression, substitute a number for the variable and then find the value.

39. “EVALUATE” Doesn’t mean to let me know how much you like it or hate it! “EVALUATE” means to solve it!

40. We substitute the variable? What does it mean to be a “substitute teacher”?

41. 1. Evaluate each expression to find the missing values in the tables. WARM-UP x 10 7 5 x 1 3 5 7 21 35 x – 5 2. Find an expression for the table. 5 2 0 7x7x 3. Evaluate 8x for x = 5. 4. Evaluate 4x – 1 for x = 12. 40 47

42. If X = 5, then… 8 - X = ? = 3

43. If X = 2, then… 5 + X = ? = 7

44. If X = 4, then… 3 x = 32 ?

45. If X = 4, then… 3 x = 12

46. When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.” Writing Math

47. If X = 5, then… 3 x = 35 ?

48. If X = 5, then… 3 x = 15

49. If X = 5, then… 2 x = ?

50. If X = 5, then… 2 x = 10

51. If X = 10, then… X 2 ? ?

52. X 2 ? 5

53. If X = 12, then… X 6 ? ?

54. X 6 ? 2

55. Evaluate the expression to find the missing values in the table. Substitute for y in 5  y. y 5  y 16 27 35 80 y = 16; 5  16 = 80 135 175 27135 35175 y = 27; 5  = y = 35; 5  = The missing values are 135 and 175.

56. Evaluate the expression to find the missing values in the table. Additional Example 1B: Evaluating Algebraic Expressions Substitute for z in z  5 + 4. z z  5 + 4 20 45 60 8 z = 20; 20  5 + 4 = 8 z = 45; __  5 + 4 = __ z = 60; __  5 + 4 = __ 13 16 45 13 60 16 The missing values are 13 and 16.

57. Try This: Example 1A Evaluate the expression to find the missing values in the table. Substitute for x in x  9. x x  9 18 36 54 2 x = 18; 18  9 = 2 4 6 4 54 6 x = 36;  9 = x = 54;  9 = 36 The missing values are 4 and 6.

58. Evaluate the expression to find the missing values in the table. Try This: Example 1B Substitute for z in 8  z + 2. z 8  z + 2 7 9 11 58 z = 7; 8  7 + 2 = 58 z = 9; 8  __+ 2 = __ z = 11; 8  __ + 2 = __ 74 90 974 1190 The missing values are 74 and 90.

59. Multiplication and division can be written without using the symbols  and . Instead of... You can write... x  3 x  3 35 ÷ y x(3) 3x3x 35 y When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.” Writing Math

60. Find an expression for the table. Additional Example 2A: Finding an Expression 39  13 = 3 n 39 52 65 3 4 5 65  13 = 5 52  13 = 4 n  13 An expression is n  13, or. n 13 2-1 Variables and Expressions Course 1

61. Find an expression for the table. Additional Example 2B: Finding an Expression 7 4 = 28 p 4 6 8 28 42 56 7 8 = 56 7 6 = 42 7 p An expression is 7 p, or 7p. 2-1 Variables and Expressions Course 1

62. Find an expression for the table. 21  3 = 7 u 21 42 63 7 14 21 63  3 = 21 42  3 = 14 u  3 An expression is u  3, or. u 3 Try This: Example 2A 2-1 Variables and Expressions Course 1

63. Find an expression for the table. Try This: Example 2B 4 5 = 20 n 5 8 11 20 32 44 4 11 = 44 4 8 = 32 4 n An expression is 4 n, or 4n. 2-1 Variables and Expressions Course 1

64. Lesson Quiz: Part 2 3. Evaluate 8x for x = 5. 4. Evaluate 4x – 1 for x = 12. 40 47 2-1 Variables and Expressions Course 1

65. Lesson 2-7 Write this in Your planner!

66. Today’s Assignment Lesson 2-1

67. Let’s Look Closer at 5 + y = 8 This is a Conditional Equation! We want to make it into a True Equation! We can tell just by glancing at it that y = 3. But, now we have to try to do something that is difficult. Pretend you don’t know that y = 3!