CCBC Math 081 Third Edition Order of Operations Section 1.7 7 Pages 1.7 Order of Operations Now you know how to perform all the operations – addition, subtraction, multiplication, division, exponents, and roots. But what if we have a problem that contains more than one operation? For instance, what if we have the problem 5 3 4 ? What operation should we perform first – the addition, the exponent, or the multiplication? It is important that everyone do the problem the same way in order to get the same answer. 2 For this reason, mathematicians developed a set of rules for evaluating problems that involve more than one arithmetic operation. The rules, called the Order of Operations, specify the order in which the computations should be performed. The Order of Operations is given below. It is important to follow these rules, one step at a time, in the order in which they are presented. ORDER OF OPERATIONS Step 1: Parentheses If there are any operations in parentheses, those computations should be performed first. Step 2: Exponents and Roots Simplify any numbers being raised to a power and any numbers under the symbol. Step 3: Multiplication and Division Do these two operations in the order in which they appear, working from left to right. Step 4: Addition and Subtraction Do these two operations in the order in which they appear, working from left to right. To help remember the Order of Operations, try using the phrase in the box on the left below. Please Excuse My Dear Aunt Sally Parentheses Exponents and Roots Multiplication and Division . . . working from left to right Addition and Subtraction . . . working from left to right 61 CCBC Math 081 Third Edition Order of Operations Section 1.7 7 Pages Before we present some examples using the Order of Operations, keep in mind that the sign of a number always precedes the number. Consider the following problems. 5 22 5 (2) 2 5 (2) 2 54 54 54 1 1 9 Evaluate 5 3 4 . Step 1 – Parentheses. There are none. 5 32 4 2 Example 1: 5 32 4 Step 2 – Exponents and Roots. We have an exponent, 3 gives 9. 5 9× 4 Step 3 – Multiplication and Division. We multiply 9 4 and get 36. 5+36 Step 4 – Addition and Subtraction. We add 5 36 and get 41. 41 The answer is 41. 2 Practice 1: Evaluate 23 30 5 . Watch it: http://youtu.be/ERXOGK6zBkw Example 2: Evaluate 8 5 (4 9) . Answer: 14 8 5 (4 9) Step 1 – Parentheses. We do the multiplication in the parentheses, 4 9 gives 36. 85 36 Step 2 – Exponents and Roots. There are none. 85 36 Step 3 – Multiplication and Division. There are none. - 8+536 Step 4 – Addition and Subtraction. Since the addition comes before the subtraction, we add 8 5 and get –3. -3-36 Step 4 – Addition and Subtraction (continued). We change the subtraction problem to an addition problem by adding the opposite. -3+-36 Step 4 –Addition and Subtraction (continued). Now we add. 39 The answer is – 39. 62 CCBC Math 081 Third Edition Order of Operations Practice 2: Evaluate 7 4 (8 3) . Watch it: http://youtu.be/9wbr3PBo1Ko Example 3: Evaluate 80 4(2) 9 . Section 1.7 7 Pages Answer: -21 Remember that the 4(2) means multiplication. 80 4(2) 9 Step 1 – Parentheses. There are no operations in parentheses. 80 4(2) Step 2 – Exponents and Roots. We have a root, 9 9 is 3. 80÷4(2)3 Step 3 – Multiplication and Division. Working left to right, the division comes first. We divide 80 4 and get 20. 20(-2) 3 Step 3 – Multiplication and Division (continued). We multiply 20(2) and get –40. -40+3 Step 4 – Addition and Subtraction. Add (40) 3 and get – 37. 37 The answer is – 37. Practice 3: Evaluate 45 5(3) 25 . Watch it: http://youtu.be/ebYCY5KYyYE Example 4: 2 Evaluate 4 (2 14) ( 3) . Answer: -22 42 (2-14) (3) Step 1 – Parentheses. There is a subtraction in the parentheses. Change the subtraction problem 2 14 to an addition problem. 42 (2+-14) (3) Step 1 – Parentheses (continued). Do the addition problem in the parentheses. Add 2 (14) to get –12. -42 (12) (3) Step 2 – Exponents and Roots. Evaluate 42 and keep the negative sign in front. We get –16. 16 Step 3 – Multiplication and Division. We divide (12) (3) which gives 4. (-12)÷(-3) -16 -4 Step 4 – Addition and Subtraction. We will change the subtraction problem to an addition problem. -16+ (-4) Step 4 – Addition and Subtraction (continued). Now add. 20 The answer is –20. 63 CCBC Math 081 Third Edition Order of Operations Practice 4: 2 Evaluate 5 (5 12) (3) . Watch it: http://youtu.be/RvZcaTsL5mc Example 5: Evaluate 32 (6 4 64) (5) 2 . 32 (6 4 64 ) (5) 2 Section 1.7 7 Pages Answer: -46 Step 1 – Parentheses. There is a subtraction, an addition, and a root in the parentheses. Do the root first, 64 is 8. 32 (6 - 48) (5) 2 Step 1 – Parentheses (continued). There is a subtraction and an addition in the parentheses. We do the subtraction since it comes first. Subtract 6 4 to get 2. 32 (2+8)(5) 2 Step 1 – Parentheses (continued). There is an addition left in the parentheses. Add 2 8 which is 10. 32 (10)(5) 2 Step 2 – Exponents and Roots. Evaluate 32 to get 9. 9 (10)×(-5) 2 Step 3 – Multiplication and Division. Do the multiplication since it comes before the division. So, 10 (5) gives –50. 9(-50) ÷2 Step 3 – Multiplication and Division (continued). Divide (50) 2 to get –25. 9-(-25) Step 4 – Addition and Subtraction. We will change the subtraction problem to an addition problem. 9+25 Step 4 – Addition and Subtraction (continued). Now add. 34 The answer is 34. 16 (8 5 32 ) (3) 2 . Practice 5: Evaluate Watch it: http://youtu.be/S5tPbqzNt5E 64 Answer: 12 CCBC Math 081 Third Edition Example 6: Order of Operations Section 1.7 7 Pages Evaluate 3 4 5 . This problem contains the absolute value symbol. Where does this fit in the order of operations? If you look back, you will find that it is not specifically mentioned in the Order of Operations steps. However, in Section 1.2 of this chapter we learned that the absolute value symbol is treated as parentheses for the purpose of order of operations. This is because it functions as a grouping symbol just as parentheses do. Therefore, absolute value is included in Step 1 of the Order of Operations. -3 - 4 5 -3+ -4 5 Step 1 – Parentheses (continued). Do the addition problem inside the absolute value symbol. Add 3 4 to get –7. -7 Step 1 – Parentheses (continued). Since there is just one number inside the absolute value symbol, we now apply the definition of absolute value. We know that the absolute value of any non-zero number is positive. So, 7 7 Step 1 – Parentheses. There are no parentheses, but there is an absolute value symbol. It is treated as parentheses for the purpose of order of operations. The absolute value acts as a grouping symbol, so the operation within the absolute value symbol must be performed before we apply the definition of absolute value. In this case, we must do the subtraction problem 3 4 first. How? By changing it to an addition problem. Step 2 – Exponents and Roots. There are no exponents or roots. Step 3 – Multiplication and Division. There is nothing to multiply or divide. 7+5 = 12 Step 4 – Addition and Subtraction. We do the addition problem and get 12. The answer is 12. Practice 6: Evaluate 5 | 3 6 | . Watch it: http://youtu.be/8kOVJX8lD_s Answer: 8 In all these example problems, we performed one operation at a time, and we were careful to bring down the rest of the problem to the next step. It is very important for you to do the same as you complete the practice exercises that follow. Watch All: http://youtu.be/h0XUAeHKJRs 65 CCBC Math 081 Third Edition Order of Operations Section 1.7 7 Pages 1.7 Order of Operations Exercises Evaluate each of the following expressions. Remember that multiplication may be represented with parentheses, “ ” or “ ” symbols. 1. 3 5 8 15. 16 2 9 ( 3) 2. 15 ( 3) 10 16. 4 2 7 32 3. 5 112 3 17. 4 (2 7) 25 4. 62 4 2 18. 3 23 5 40 5. 3 (6)2 20 19. 4(32 ) 15 ( 4) 6. 52 36 20. 22 5 (3 1) 7. 8 (15 3) 4 21. 30 6 9 8. 2 (8 10) 2 22. 15 (23 ) (4)(3) 9. 6 2 (1 5) 23. 20 2 22 5 (2) 10. 6(3 8 4) 24. 42 (8) 11. 4 5 (6 2) 25. 8 24 (25 5) 81 26. 3 (2 9) 4 (7 2) 27. 4 6 (2 7)2 (17 12) 28. 6 8 9(8) 12. 6 13. 9 4(2 3) 14. 2 8 4 16 52 3 66 3 27 2 4 (16 9) CCBC Math 081 Third Edition Order of Operations Section 1.7 7 Pages 1.7 Order of Operation Exercises Answers 1. 37 15. 11 2. 5 16. – 19 3. 123 17. –4 4. 38 18. 29 5. 32 19. – 25 6. 31 20. – 14 7. 24 21. 10 8. 3 22. 21 9. 14 23. 0 10. 30 24. – 23 11. – 24 25. 124 12. 84 26. – 15 13. 13 27. – 26 14. 40 28. – 109 67 CCBC Math 081 Third Edition Chapter 1 Summary CHAPTER 1 SUMMARY Integers Section 1.1 Natural Numbers {1, 2, 3, 4, 5 … } Integers {…, -4, -3, -2, -1, 0, 1, 2, 3, 4, … } Whole Numbers {0, 1, 2, 3, 4, 5 … } Negative Section The Absolute Value of 0 is 0. Section 1.3 The Absolute Value of all other real numbers is positive. 0 0 1.2 Positive 6 6 6 6 Addition SSS Method 5 3 53 8 5 3 8 Same – signs of #s are the same Sum – add absolute values Same – answer has same sign as original #s DDD Method 4 (6) 64 2 4 (6) 2 Different – signs of #s are different Difference – subtract absolute values Dominant – answer has sign of bigger # Section 1.4 Subtraction – use the “Add the Opposite” method Subtracting a Positive becomes Adding a Negative: Subtracting a Negative becomes Adding a Positive: 5 8 5 (8) 5 (8) 5 8 Multiplication and Division Section 1.5 a b a ( b) a (b) a b Same Signs Positive answer Different Signs Negative answer (3) (4) 12 (12) (3) 4 3 (4) 12 12 3 4 68 Use of Zero n 00 0n 0 n 0 undefined CCBC Math 081 Third Edition Section 1.6 Chapter 1 Summary Exponents a n - the exponent (n) tells how many times the base (a) is multiplied with itself Roots 3 Section 1.7 (6)2 (6) (6) 36 62 6 6 36 n 62 (6 6) 36 Note: a 0 1 a = the number that, when raised to the power n, gives a 8 means 3 . The answer is 2 because 23 2 2 2 8 . Order of Operations Please Excuse My Dear Aunt Sally Parentheses Exponents and Roots Multiplication and Division (working left to right) Addition and Subtraction (working left to right) 69 4 (9 7)3 5 4 23 5 4 8 5 4 40 44 CCBC Math 081 Third Edition Chapter 1 Review CHAPTER 1 Chapter Review 1. Circle each number system that the number –34 belongs to: Natural Numbers Whole Numbers Integers 2. Circle all the positive integers in the list of numbers: 1.2 0 5.8 7 A 3. What is the value of each of the points named by the capital letters on the number line? 4. Place the numbers 4 and –1 on the number line: 0 5. 8 18. 53 6. 27 (14) 19. 170 7. 38 56 20. 122 8. 24 (24) 21. (12)2 9. 20 8 22. (5)3 17 (9) 23. 3 10. 11. 6 12 12. 42 (7) 13. 90 (3) 14. 14 0 15. 0 56 16. 12 (4) 17. 5(8)(4) 70 27 49 25. 61 3 4 26. 5 27. 52 3(1 4) 40 28. 22 3 8 23 29. 50 2 52 9 30. 4 6 72 1 2 3 B 0 24. 9 81 4 5 7 6 CCBC Math 081 Third Edition Chapter 1 Review Chapter 1 Review Answers 1. Natural Numbers 2. 1.2 3. A = –3 4. 0 7 Whole Numbers 5.8 9 1 2 3 Integers 6 B= 5 -1 0 4 5. –8 18. 125 6. –41 19. 1 7. 18 20. –144 8. 0 21. 144 9. –28 22. –125 10. –8 23. 3 11. –72 24. 7 12. 6 25. –6 13. –30 26. –2 14. 0 27. 24 15. 0 28. 7 16. 48 29. –50 17. –160 30. 74 71