EXAMPLE 1 Using the Commutative Property Tour Biking You are going on a 400 mile bike trip. You plan to cycle at an average speed of 12 miles per hour for 7 hours a day. Can you complete the trip in 5 days? SOLUTION Write a verbal model to find the total distance you can cycle in 5 days.
Using the Commutative Property EXAMPLE 1 Using the Commutative Property 12 7 5 = Substitute known values. 12 5 7 = Commutative property of multiplication 60 7 = Multiply. 420 = Multiply.
EXAMPLE 1 Using the Commutative Property The unit for the result is miles. days = miles miles hour hours day Because 400 miles is less than the 420 miles you can cycle in 5 days, you can complete the trip in 5 days. Answer
Using the Commutative Property EXAMPLE 2 Using the Commutative Property –54 + 35 – 16 = –54 + 35 + (–16 ) Change subtraction to addition. = –54 + (–16) + 35 Commutative property of addition = –70 + 35 Add –54 and –16. = –35 Add –70 and 35.
GUIDED PRACTICE for Examples 1 and 2 1. What If? Suppose in Example 1 you only want to bike for 6 hours a day at an average speed of 14 miles per hour. Can you complete the trip in 6 days? SOLUTION Write a verbal model to find the total distance you can cycle in 6 days.
GUIDED PRACTICE for Examples 1 and 2 14 6 6 = 14 6 6 = 84 6 = 504 = 14 6 6 = Substitute known values. 14 6 6 = Commutative property of multiplication 84 6 = Multiply. 504 = Multiply.
GUIDED PRACTICE for Examples 1 and 2 The unit for the result is miles. days = miles miles hour hours day Answer Yes , Because 400 miles is less than the 504 miles you can cycle in 6 days, you can complete the trip in 6 days.
Use the commutative property to evaluate the expression. GUIDED PRACTICE for Examples 1 and 2 Use the commutative property to evaluate the expression. 4 (–9) 25 2. 4 25 (–9) = Commutative property of multiplication 100 (–9) = Multiply 4 and 25. –900 = Multiply.
Use the commutative property to evaluate the expression. GUIDED PRACTICE for Examples 1 and 2 Use the commutative property to evaluate the expression. 3. –13 + 34 –7 = –13 + 34 + (–7) Change subtraction to addition. = –13 + (–7) + 34 Commutative property of addition = –20 + 34 Add –13 and –7. = 14 Add –20 and 34.
Use the commutative property to evaluate the expression. GUIDED PRACTICE for Examples 1 and 2 Use the commutative property to evaluate the expression. 4. 3 7 8 + 4 + 3 7 = + 8 + 4 Commutative property of addition 4 7 3 + + 8 = Associative property of addition 7 + 8 = Add inside grouping symbols. 1 + 8 = Add. = 9
Using the Associative Property EXAMPLE 3 Using the Associative Property 3 5 + 2 = 3 5 + 2 Associative property of addition 5 + 3 = Add fractions. Write as one. 5 1 + 3 = 4 = Add.
Using the Associative Property EXAMPLE 4 Using the Associative Property 5 (11 2) 5 (2 11) = Commutative property of multiplication (5 2) 11 = Associative property of multiplication 10 11 = Multiply inside grouping symbols. 110 = Multiply.
Use properties to evaluate the expression. GUIDED PRACTICE for Examples 3 and 4 Use properties to evaluate the expression. 5. 18 + (–34 + 12) = 18 + (12 + (–34)) Commutative property of addition = (18 + 12) + (–34) Associative property of addition = 30 + (–34) Add inside grouping symbols. = –4 Add.
Use properties to evaluate the expression. GUIDED PRACTICE for Examples 3 and 4 Use properties to evaluate the expression. 4 5 8 + 1 + 4 5 = + 8 + 1 Commutative property of addition 1 5 4 + = + 8 Associative property of addition 5 + 8 = Add inside grouping symbols. 1 + 8 = Add. 9 =
Use properties to evaluate the expression. GUIDED PRACTICE for Examples 3 and 4 Use properties to evaluate the expression. 12 (6 ) 1 12 = 12 6) ( 1 Commutative property of multiplication = 12 6 1 ( ) Associative property of multiplication = 1 6 Multiply inside grouping symbols. = 6 Multiply.
Use properties to evaluate the expression. GUIDED PRACTICE for Examples 3 and 4 Use properties to evaluate the expression. 6 5 (3 ) = 3) ( 5 6 Commutative property of multiplication = ( 5 6 ) 3 Associative property of multiplication = 1 3 Multiply inside grouping symbols. = 3 Multiply.
GUIDED PRACTICE for Examples 3 and 4 Evaluate the expression using mental math. 4 ( 23) 1 4 = 23 –4 ( 50 ) 46 = – 4600 –21 – (–29) = (–6 ) 10 1 ( ) = –6