2. 2-1 Variables and Expressions Course 1 6 th Grade Math HW: Page 50 #5-17 all

3. 2-1 Variables and Expressions Course 1 Who did not take the Chapter 1 Test?

4. Course 1 Warm Up Lesson Presentation Lesson Presentation Problem of the Day 2-1 Variables and Expressions Course 1

5. Warm Up Simplify. 1. 4 + 7  3  1 2. 87  15  5 3. 6(9 + 2) + 7 4. 35  7  5 24 84 73 25 2-1 Variables and Expressions Course 1

6. Problem of the Day How can the digits 1 through 5 be arranged in the boxes to make the greatest product?  4 3 1 5 2 2-1 Variables and Expressions Course 1

7. Today’s Learning Goal Learn to identify and evaluate expressions. 2-1 Variables and Expressions Course 1

8. Vocabulary variable constant algebraic expression 2-1 Variables and Expressions Course 1

9. A variable is a letter or symbol that represents a quantity that can change. A constant is a quantity that does not change. 2-1 Variables and Expressions Course 1

10. An algebraic expression contains one or more variables and may contain operation symbols. p  7 is an algebraic expression. 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. 2-1 Variables and Expressions Course 1

11. Evaluate the expression to find the missing values in the table. Additional Example 1A: Evaluating Algebraic Expressions 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  = 2-1 Variables and Expressions Course 1 The missing values are 135 and 175.

12. 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 2-1 Variables and Expressions Course 1 The missing values are 13 and 16.

13. 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 2-1 Variables and Expressions Course 1 The missing values are 4 and 6.

14. 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 2-1 Variables and Expressions Course 1 The missing values are 74 and 90.

15. 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 2-1 Variables and Expressions Course 1

16. 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

17. 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

18. 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

19. 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

20. 1. Evaluate each expression to find the missing values in the tables. Lesson Quiz: Part 1 x 10 7 5 x 1 3 5 7 21 35 x – 5 2. Find an expression for the table. 5 2 0 7x7x 2-1 Variables and Expressions Course 1

21. 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