Lesson Variable and Algebraic Expressions.ppt
- 1. 2-7 Variables and Algebraic Expressions Course 2 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation
- 2. Warm Up Evaluate. 1. 5(7) – 1 2. 7(18 – 11) 3. 22 + 17 8 + 3 4. 36 + 15(40 – 35) 5. 33 + 7(12 – 4) 34 49 161 Course 2 2-7 Variables and Algebraic Expressions 111 83
- 3. Problem of the Day How much will it cost to cut a log into eight pieces if cutting it into four pieces costs $12? $28 Course 2 2-7 Variables and Algebraic Expressions
- 4. Learn to evaluate algebraic expressions. Course 2 2-7 Variables and Algebraic Expressions
- 5. Vocabulary variable constant algebraic expression evaluate Insert Lesson Title Here Course 2 2-7 Variables and Algebraic Expressions
- 6. Course 2 2-7 Variables and Algebraic Expressions Ron Howard was born in 1954. You can find out what year Ron turned 16 by adding the year he was born to his age. 1954 + 16 In algebra, letters are often used to represent numbers. You can use a letter such as a to represent Ron Howard’s age. When he turns a years old, the year will be 1954 + a.
- 7. Course 2 2-7 Variables and Algebraic Expressions The letter a has a value that can change, or vary. When a letter represents a number that can vary, it is called a variable. The year 1954 is a constant because the number cannot change. An algebraic expression consists of one or more variables. It usually contains constants and operations. For example, 1954 + a is an algebraic expression for the year Ron Howard turns a certain age.
- 8. Course 2 2-7 Variables and Algebraic Expressions To evaluate an algebraic expression, substitute a number for the variable. Age Year born + age = year at age 16 1954 + 16 1970 18 1954 + 18 1972 21 1954 + 21 1975 36 1954 + 36 1990 a 1954 + a
- 9. Evaluate k + 9 for each value of k. Additional Example 1: Evaluating Algebraic Expressions Course 2 2-7 Variables and Algebraic Expressions A. k = 5 k + 9 5 + 9 14 Substitute 5 for k. Add. B. k = 2 k + 9 2 + 9 Substitute 2 for k. 11 Add.
- 10. Try This: Example 1 Insert Lesson Title Here Course 2 2-7 Variables and Algebraic Expressions Evaluate a + 6 for each value of a. A. a = 3 a + 6 3 + 6 9 Substitute 3 for a. Add. B. a = 5 a + 6 5 + 6 Substitute 5 for a. 11 Add.
- 11. Course 2 2-7 Variables and Algebraic Expressions Multiplication and division of variables can be written in several ways, as shown in the table. Multiplication Division 7t 7 · t 7(t) 7 t q 2 q ÷ 2 q/2 ab a · b a(b) a b s r s ÷ r s/r When evaluating expressions, use the order of operations.
- 12. Evaluate the expression for the given value of the variable. Additional Example 2A: Evaluating Algebraic Expressions Involving Order of Operations Course 2 2-7 Variables and Algebraic Expressions A. 4x – 3 for x = 2 4(2) – 3 8 – 3 5 Substitute 2 for x. Multiply. Subtract.
- 13. Additional Example 2B & 2C: Evaluating Algebraic Expressions Involving Order of Operations Course 2 2-7 Variables and Algebraic Expressions B. s ÷ 5 + s, for s = 15 15 ÷ 5 + 15 3 + 15 18 C. 5x2 + 3x, for x = 2 5(2)2 + 3(2) 5(4) + 3(2) 20 + 6 26 Substitute 15 for s. Divide. Add. Substitute 2 for x. Evaluate the power. Multiply. Add.
- 14. Try This: Example 2A Insert Lesson Title Here Course 2 2-7 Variables and Algebraic Expressions Evaluate each expression for the given value of the variable. A. 3x – 2 for x = 3 3(3) – 2 9 – 2 7 Substitute 3 for x. Multiply. Subtract.
- 15. Try This: Example 2B & 2C Insert Lesson Title Here Course 2 2-7 Variables and Algebraic Expressions B. r ÷ 3 + r, for r = 12 12 ÷ 3 + 12 4 + 12 16 C. 4y2 + 2y, for y = 3 4(3)2 + 2(3) 4(9) + 2(3) 36 + 6 42 Substitute 12 for r. Divide. Add. Substitute 3 for y. Evaluate the power. Multiply. Add.
- 16. Evaluate Additional Example 3: Evaluating Algebraic Expressions with Two Variables Course 2 2-7 Variables and Algebraic Expressions 6 a + 4b, for a = 3 and b = 2. 6 a + 4b 6 3 + 4(2) 2 + 8 10 Substitute 3 for a and 2 for b. Divide and multiply from left to right. Add.
- 17. Try This: Example 3 Insert Lesson Title Here Course 2 2-7 Variables and Algebraic Expressions Evaluate 8 w + 2x, for w = 4 and x = 2. 8 w + 2x 8 4 + 2(2) 2 + 4 6 Substitute 4 for w and 2 for x. Divide and multiply from left to right. Add.
- 18. Lesson Quiz Evaluate n + 7 for each value of n. 1. n = 25 2. n =31 Evaluate each algebraic expression for the given value of the variables 3. 6y – 5 for y = 7 4. 4x2 + 3x for x = 6 5. + 3y for x = 4 and y = 3 6. The expression 7d gives the number of days in d weeks. Evaluate 7d for d = 12. How many days are in 12 weeks? 38 32 Insert Lesson Title Here 37 162 Course 2 2-7 Variables and Algebraic Expressions 56 x 23 84