240 likes | 360 Views
A B C D. Find 9 – (–1). A. 8 B. 9 C. 10 D. 11. Find –3 – (–21). A. –24 B. –18 C. 19 D. 18. Evaluate the expression a – b if a = –7 and b = 9. A. –16 B. –2 C. 2 D. 16. 5-Minute Check 1. Splash Screen.
E N D
A B C D Find 9 – (–1). A. 8 B. 9 C. 10 D. 11 Find –3 – (–21). A. –24 B. –18 C. 19 D. 18 Evaluate the expression a – b if a = –7 and b = 9. A. –16 B. –2 C. 2 D. 16 5-Minute Check 1
You multiplied integers using algebra tiles. (Explore 2–4) • Multiply integers. • Simplify algebraic expressions. Then/Now
Multiply Integers with Different Signs A.Find 8(–9). 8(–9) = –72 The factors have different signs. The product is negative. Answer: –72 Example 1
Multiply Integers with Different Signs B.Find –9(11). –9(11) = –99 The factors have different signs. The product is negative. Answer: –99 Example 1
A B C D A. Find –4(12). A. –3 B. –46 C. 48 D. –48 Example 1
A B C D B. Find 6(–2). A. 12 B. –12 C. –3 D. –8 Example 1
Multiply Integers with the Same Sign A.Find –4(–16). –4(–16) = 64 The factors have the same sign. The product is positive. Answer: 64 Example 2
Multiply Integers with the Same Sign B.Find –9(–6). –9(–6) = 54 The product is positive. Answer: 54 Example 2
A B C D A. Find –3(–8). A. 24 B. –24 C. –11 D. 23 Example 2
A B C D B. Find –8(–9). A. –72 B. –17 C. 17 D. 72 Example 2
Multiply Integers with Different Signs SKI LIFTSA ski lift descends the side of a mountain at the rate of 450 feet per minute. What is the lift’s change in altitude after 7 minutes? UnderstandYou need to find how many feet the ski lift descends. Plan The word descends means move downward, so the rate per minute is represented by –450. Multiply –450 times 7 to find the change after 7 minutes. Solve 7(–450) = –3150 feet The product is negative. Example 3
Multiply Integers with Different Signs Answer: So, the change in altitude is –3150 feet. Check7(–500) is –3500. –3150 is close to –3500. Example 3
A B C D ELEVATORS An elevator is descending at the rate of 5 feet per second. What is the change in altitude after 6 seconds? A. –30 feet B. –11 feet C. 11 feet D. 30 feet Example 3
Multiply More Than Two Integers Find 7(–11)(4). Method 1Use the Associative Property 7(–11)(4) = [7(–11)](4) Associative Property = (–77)(4) 7(–11) = –77 = –308 (–77)(4) = –308 Example 4
Multiply More Than Two Integers Method 2Use the Commutative Property 7(–11)(4) = 7(4)(–11) Commutative Property = 28(–11) 7(4) = 28 = –308 28(–11) = –308 Answer: –308 Example 4
A B C D Find –3(8)(5). A. –120 B. –25 C. 25 D. 120 Example 4
Simplify Algebraic Expressions Simplify 8a(–5b). 8a(–5b) = (8)(a)(–5)(b) = (8 ● –5)(a ● b) Commutative Property of Multiplication = –40ab (8 ● –5) = –40, a ● b = ab Answer: –40ab Example 5
A B C D Simplify –6(2c). A. 12c B. –12c C. 8c D. –8c Example 5
Evaluate Algebraic Expressions Evaluate –3xy if x = –4 and y = 9. –3xy = –3(–4)(9) Replace x with –4 and y with 9. = [–3(–4)](9) Associative Property of Multiplication = 12(9)The product of –3 and –4 is positive. = 108 The product of 12 and 9 is positive. Answer: 108 Example 6
A B C D Simplify 5m(–7n). A. –2mn B. –12mn C. 35mn D. –35mn Example 6