Lesson Menu Main Idea NGSSS Key Concept:Multiply Integers with Different Signs Example 1:Multiply Integers with Different Signs Example 2:Multiply Integers with Different Signs Key Concept:Multiply Integers with the Same Sign Example 3:Multiply Integers with the Same Sign Example 4:Multiply Integers with the Same Sign Example 5:Multiply Integers with the Same Sign Example 6:Real-World Example Example 7:Add Integers with the Same Sign Five-Minute Check

Main Idea/Vocabulary Use the rules for multiplying integers.

NGSSS MA.7.A.3.1 Use and justify the rules for adding, subtracting, multiplying, dividing, and finding the absolute value of integers. Also addresses MA.7.A.3.2.

Key Concept

Example 1 Multiply Integers with Different Signs Find 5(–4). 5(–4) = –20The integers have different signs. The product is negative. Answer: –20

Example 1 CYP A.–14 B.–9 C.–5 D.14 Find 2(–7).

Example 2 Find –3(9). Multiply Integers with Different Signs –3(9) = –27The integers have different signs. The product is negative. Answer: –27

Example 2 CYP A.22 B.13 C.–13 D.–22 Find –2(11).

Key Concept 3

Example 3 Multiply Integers with the Same Sign Find –6(–8). –6(–8) = 48The integers have the same sign. The product is positive. Answer: 48

Example 3 CYP A.4 B.3 C.–4 D.–5 Find –4(–1).

Example 4 Find (–8) 2. Multiply Integers with the Same Sign (–8) 2 = (–8)(–8)There are two factors of –8. = 64The product is positive. Answer: 64

Example 4 CYP A.–2 B.–1 C.1 D.2 Find (–1) 2.

Example 5 Multiply Integers with the Same Sign Find –2(–5)(–6). –2(–5)(–6) = [–2(–5)](–6)]Associative Property = 10(–6)–2(–5) = 10 = –6010(–6) = –60 Answer: –60

Example 5 CYP A.–84 B.–26 C.54 D.84 Find –6(–7)(–2).

Example 6 MINES A mine elevator descends at a rate of 300 feet per minute. How far below Earth’s surface will the elevator be after 5 minutes? If the elevator descends 300 feet per minute then after 5 minutes the mine elevator will be at 5(–300) or –1,500 feet. The mine elevator will descend to 1,500 feet below the Earth’s surface. Answer: –1,500 feet or 1,500 feet below Earth’s surface

Example 6 CYP A.+30ºF B.+13ºF C.–13ºF D.–30ºF FOOD John’s freezer decreases the temperature of a casserole by 3ºF every minute. What is the change in temperature after 10 minutes?

Example 7 Add Integers with the Same Sign ALGEBRA Evaluate abc if a = –3, b = 5, and c = –8. abc = –3(5)(–8)Replace a with –3, b with 5, and c with –8. = (–15)(–8)Multiply –3 and 5. = 120Multiply –15 and –8. Answer: The solution is 120.

Example 7 CYP A.–12 B.–11 C.11 D.12 ALGEBRA Evaluate rst if r = –1, s = 2, and t = –6.

A.–26 B.–16 C.–105 D.105 Find 21(–5). Five Minute Check 1

A.28 B.11 C.–28 D.–11 Find –7(–4). Five Minute Check 2

A.–81 B.–18 C.18 D.81 Find (–9) 2. Five Minute Check 3

A.17,424 B.1,233 C.441 D.135 Evaluate 9(x 2 + y 2 ) if x = –4 and y = 11. Five Minute Check 4

A.–44 B.–15 C.15 D.44 Evaluate –xy if x = –4 and y = 11. Five Minute Check 5

A.–38g B.–24g C.–24 + g D.–24 + 3g What is –3(8g) simplified? Five Minute Check 6