1.3 variables and expressions 1
- 1. Lesson 1.3 , For use with pages 13-18 Evaluate the expression. 1. 5 • 6 + 3 • 2 Reminder : You need your math book and calculator in class today! 2. 21 (9 – 2)
- 2. Lesson 1.3 , For use with pages 13-18 Evaluate the expression. 1. 5 • 6 + 3 • 2 Reminder : You need your math book and calculator in class today! ANSWER 36 ANSWER 3 2. 21 (9 – 2)
- 3. Lesson 1.3 Variables and Expressions Day 1 Objective: To be able to write and evaluate variable expressions.
- 4. Variable : symbol, usually a letter, that represents one or more numbers. Variable Expression : consists of numbers, variables, and operations. Algebraic Expression : is one or more algebraic terms in a phrase. It can include variables, constants, and operating symbols, such as plus and minus signs. For example: 3x 2 + 2y + 7xy + 5 Vocabulary
- 5. Vocabulary Name some synonyms for addition, subtraction, multiplication and division. See page 14 in your textbook. Addition Subtraction Multiplication Division Plus The sum of Increased by Total More than Added to Minus The difference of Decreased by Fewer than Less than Subtracted from Times The product of Multiplied by Of Twice Divided by The quotient of Separate into equal parts
- 6. EXAMPLE 3 Translating Verbal Phrases Verbal Phrase Variable Expression The sum of a number and 9 The difference of a number and 21 The product of 6 and a number The quotient of 48 and a number One third of a number n + 9 n – 21 6 n 48 n 3 1 n
- 7. GUIDED PRACTICE for Examples 2 and 3 Write the phrase as a variable expression using x . 8. a number increased by 15 9. 8 times a number x + 15 8 x Verbal Phrase Variable Expression
- 8. GUIDED PRACTICE for Examples 2 and 3 Evaluate the expression when a = 12 and b = 3 . 4. 9 a 5 . ab Substitute 12 for a = 9(12) = 108 Substitute 12 for a and 3 for b = (12)(3) = 36 Multiply. Multiply.
- 9. EXAMPLE 2 Evaluating Variable Expressions Evaluate the expression when x = 8 and y = 2 . a. 3 x – 5 y Substitute 8 for x and 2 for y . Multiply. Subtract. Substitute 8 for x and 2 for y . Add. b. 5( x + y ) Multiply. 3( 8 ) – 5( 2 ) = 24 – 10 = 14 = 5( 8 + 2 ) = 50 = = 5(10)
- 10. GUIDED PRACTICE for Examples 2 and 3 Evaluate the expression when a = 12 and b = 3 . 6. b ( a – 6) = 3(12 – 6) Substitute 12 for a and 3 for b = 3(6) Subtract. Multiply. = 18
- 11. GUIDED PRACTICE for Examples 2 and 3 Evaluate the expression when a = 12 and b = 3 . Substitute 12 for a and 3 for b Multiply. Subtract. = 8 Divide. 7. 6 a a – b 6(12) 12 – 3 = 72 12 – 3 = 9 72 =
- 12. Do together: Page 15 #40-43 3.8m 3.8m + 8 27
- 13. Do together: Page 15 #40-43 30x + 60y – 3z
- 14. Do together: Page 15 #40-43 13x + 15y + 2z
- 15. Do together: Page 15 #40-43
- 16. Do together: Page 15 #40-43 20 – (2.75p + 2.5d) = $1.75
- 17. Homework Page 15 #4-12 even, 13-21 all. Use Pencil Put your name, date, class period and assignment in the right hand corner of your paper. Show all your work. NWEA tomorrow! Meet in the 6 th grade computer lab. (by the office)