CHAPTER 8 Integers GET READY 412 Math Link 414 8.1 Warm Up 415 8.1 Exploring Integer Multiplication 416 8.2 Warm Up 423 8.2 Multiplying Integers 424 8.3 Warm Up 429 8.3 Exploring Integer Division 430 8.4 Warm Up 436 8.4 Dividing Integers 437 8.5 Warm Up 444 8.5 Applying Integer Operations 445 Chapter Review 452 Practice Test 456 Wrap It Up! 458 Key Word Builder 459 Math Games 460 Challenge in Real Life 461 Chapters 5–8 Review 463 Task 469 Answers 470
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The temperature helps you decide what to wear and what to do with your time. You use temperature changes at home when you boil water or turn up the heat in the winter. a) The integer chips show a temperature increase of 8 °C
from a starting temperature of –3 °C. Complete the addition expression and solve.
(–3) + ( ) = b) The number line shows a temperature decrease of 9 °C from a starting temperature of 4 °C. Complete the subtraction expression and solve.
(+4) – (+ )
= (+4) + ( ) Add the opposite.
= c) Draw integer chips to show the subtraction equation in part b).
d) The temperature changes from +5 °C to –15 °C. Draw a number line or integer chips to show the temperature change. e) Complete and solve the subtraction
expression for part d).
(+5) – ( )
= (+5) + ( )
=
The temperature change is
°C.
f) The temperature change over 4 h was –20 °C. Show how you would find the temperature
For 5 h, the temperature in Flin Flon, Manitoba, dropped by 3 °C each hour. What is the total change in temperature?
Solution
Write a multiplication expression. 5 h = +5 Temperature drop of 3 °C = Multiplication expression: (+5) × ( ) Draw 5 groups of 3 negative integer chips.
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For 4 h, the temperature in Victoria fell by 2 °C each hour. What is the total change in temperature?
h = + Temperature drop of 2 °C = Multiplication expression: ( ) × ( ) Draw 4 groups of 2 negative integer chips.
There are negative integer chips. ( ) × ( ) = The total change in temperature is °C.
• first blank = number of groups • second blank = number of integers in each group
1. David said that he could model (+3) × (–7) using 3 positive chips and 7 negative chips. Draw a model of (+3) × (–7).
Draw 3 groups of negative integer chips.
Is David correct? Circle YES or NO. Give 1 reason for your answer. ___________________________________________________________________________ ___________________________________________________________________________
2. Write each repeated addition as a multiplication statement.
a) (+1) + (+1) + (+1) + (+1) + (+1)
= ( ) × (+1)
b) (–6) + (–6)
= ( ) × ( )
3. Write each multiplication statement as a repeated addition.
a) (+3) × (+8) = ( ) + ( ) + ( )
b) (+5) × (–6)
4. Write the multiplication statement for each diagram.
Is 8 positive or negative? Repaid means she lost money.
Deep means the answer has a negative sign. Do not write the negative sign in your
statement.
Multiply 2 integers.
7. Write a multiplication statement to represent each problem.
a) The temperature increased 2 °C per hour for 6 h. What was the total temperature change? 6 h = (+ ) Temperature increase of 2 °C = +2 ( ) × ( ) = The temperature increased by °C.
b) Ayesha repaid some money she owed in 4 payments of $8 each. How much money did Ayesha repay? 4 payments = (+ ) $8 payments = ( ) ( ) × ( ) = Ayesha repaid $ .
8. An oil rig is drilling a well at 2 m/min.
How deep is the well after the first 8 min? 2 m deep = (– ) 8 min = ( ) ( ) × ( ) = The well is m deep.
9. An aircraft descends at 3 m/s for 12 s. How far does it descend? Sentence: ____________________________________________________________________
Discount means $15 off your bill. Annual means each year.
Descending means going down.
7. A telephone company offers a $15 discount per month. How much is the annual discount?
$15 discount = ( )
12 months = ( )
Multiplication statement: ( ) × ( ) =
The discount is $ .
8. Complete each statement.
a) (+6) × ( ) = +18 b) ( ) × (–2) = –10 c) ( ) × (+3) = –12 d) (–4) × ( ) = +16
9. A hot-air balloon is descending at 60 m/min.
How far does it go down in 25 min? Descending 60 m = ( ) 25 min = (+ ) Multiplication statement: ( ) × ( ) = Sentence: _________________________________________________________________
10. Astronauts train for space using deep dives on a plane.
The plane can descend at 120 m/s for 20 s. How far does the plane descend? Sentence: _________________________________________________________________
A weather balloon was launched from The Pas, Manitoba, on a still, dry day. The temperature of still, dry air drops by about 6 °C for each kilometre you go up in altitude.
altitude • height above the ground
a) Is a decrease of 6 °C written as a positive value or a negative value?
b) What is the temperature change for each of the distances above ground?
1 km: (−6) × 1 = °C temperature change
2 km: (−6) × = °C temperature change
3 km:
4 km:
5 km:
6 km:
11 km:
c) What is the temperature 11 km above ground if the ground temperature is 4 °C? ( ) + ( ) = Sentence: _______________________________________________________________ d) If the balloon drops from 11 km to 5 km, what is the change in altitude? e) As the balloon drops, will the temperature increase or decrease? f) About how much does the temperature change as the balloon drops from 11 km to 5 km?
e) 20 ÷ 4 = f) 40 ÷ 5 = 4. Fill in the missing integers.
a) (+10) × (–4) =
b) (–2) × = (–10)
c) × (–8) = +16
d) × (–3) = (–27)
5. Fill in the blanks.
a) If 2 integers have the same sign, the product is . Examples: (–7) × (–4) = and (+7) × (+4) = b) If 2 integers have different signs, the product is . Examples: (–5) × (+6) = and (+5) × (−6) =
Draw integer chips to solve each statement. a) (+14) ÷ (+7) Draw 14 positive integer chips. Separate the chips into groups of 7. Circle the groups.
There are groups of 7 positive chips, so the quotient is .
(+14) ÷ (+7) = b) (–9) ÷ (–3) Draw negative integer chips. Separate the chips into groups of 3. Circle the groups.
How many groups of (–3) are there?
So, the quotient is .
(–9) ÷ (–3) = c) (–16) ÷ (+2) Draw integer chips. Separate the chips into groups of . Circle the groups. There are chips in each group, so the quotient is .
The temperature in Wetaskiwin, Alberta, was falling by 2 °C each hour. The temperature fell a total of 10 °C. How many hours did it take the temperature to fall? Solution Write a division expression. Temperature falling 2 °C = (–2) Total decrease of 10 °C = (–10) Division expression: (–10) ÷ ( )
Draw 10 negative integer chips in groups of . -
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It took h for the temperature to fall 10 °C.
The temperature in Buffalo Narrows, Saskatchewan, was falling by 3 °C each hour. The temperature fell 12 °C altogether. How many hours did it take the temperature to fall?
Falling 3 °C per hour = ( )
Total decrease of 12 °C = ( )
The total number of hours = ( ) ÷ ( )
Draw negative integer chips in groups of 3. Circle groups of 3 chips. There are groups, so the quotient is .
sign rule for division • the quotient of two integers with the same sign is positive ÷ =+ + ++ ÷ =- - • the quotient of two integers with different signs is negative ÷ =- - -+ ÷ =- +
a) Calculate (+6) ÷ (+2).
Solution
Divide the numbers: 6 ÷ 2 = 3 Apply the sign rule: The quotient of 2 integers with the same sign is positive. (+6) ÷ (+2) = +3 b) Calculate (–12) ÷ (–6).
Solution
Divide the numbers: 12 ÷ 6 = Apply the sign rule: The quotient of 2 integers with the same sign is .
(–12) ÷ (–6) = + c) Calculate (–20) ÷ (+4).
Solution
Divide the numbers: 20 ÷ 4 = Apply the sign rule: The quotient of 2 integers with different signs is negative.
Pay means the answer has a negative sign. Do not write the negative sign.
Working Example 2: Apply Integer Division
Daria and 4 friends went out for lunch. The total cost was $85. They divided the cost equally. How much did each person pay? Solution Write a division statement. Total cost of $85 = (–85)
Daria plus 4 friends = (+ )
(–85) ÷ (+5) = (– )
Each person has to pay $ . Check: Use multiplication to check the division. Answer × divisor = cost of the bill
(– ) × (+5) =
Pierre paid $42 for himself and 2 friends to go to a science museum. What was the cost for each person? Total cost of $42 = ( ) Number of people = ( ) ( ) ÷ ( ) = Each person had to pay $ .
__________________________________________________________________________ 2. Stefani said that the quotients of (–8) ÷ (–4) and (+8) ÷ (+4) must be the same.
8. a) A submarine took 16 min to dive 96 m. How far did it dive per minute? Distance of dive = (– ) 16 min = (+ ) Division statement: The submarine dove m/min.
b) The submarine took 12 min to climb 96 m. How far did it climb per minute? Distance it climbed = (+ ) 12 min = ( ) Division statement: Sentence: _________________________________________________________________
9. The school spent $384 to buy 32 calculators. What was the cost of 1 calculator?
$384 spent = ( ) Number of calculators = ( ) Division statement: Sentence: ____________________________________________________________________
The temperature of still, dry air decreases by 6 °C for each kilometre increase in altitude. The temperature in Yellowknife, Northwest Territories, was –11 °C. The temperature outside a plane flying above Yellowknife was –53 °C.
a) How much lower was the temperature outside the plane than the temperature in Yellowknife?
Temperature in Yellowknife = ( ) Temperature outside the plane = ( ) Temperature change = outside plane temperature – Yellowknife temperature = ( ) – ( ) = ( ) + ( ) Add the opposite. = The temperature change was °C.
b) How high was the plane above Yellowknife?
Temperature change = ( ) Temperature drop of 6 °C per km = ( ) Height of plane = temperature change ÷ temperature drop = ( ) ÷ ( ) The plane was km above Yellowknife. Check: × =
8.5 Applying Integer Operations Working Example 1: Use the Order of Operations
order of operations • the order of steps for a calculation Step 1: Brackets. Step 2: Multiply and divide in order from left to right. Step 3: Add and subtract in order from left to right.
a) Calculate (–15) ÷ (–3) – (+4) × (–2).
Solution
(–15) ÷ (–3) – (+4) × (–2) Multiply and divide in order. = (+5) – (+4) × (–2)
In Peguis, Manitoba, the daily high temperatures for 5 days were –2 °C, –6 °C, +1 °C, +2 °C, and –5 °C. What was the mean daily high temperature for those days?
Solution To find the mean, add the integers and divide by the number of integers. Add the integers:
(–2) + (–6) + (+1) + (+2) + (–5)
= ( ) + (+1) + (+2) + (–5)
= ( ) + (+2) + (–5)
= ( ) + (–5)
=
Divide by the number of integers.
( ) ÷ 5 =
The mean daily temperature was °C.
In Resolute, Nunavut, the daily low temperatures were –6 °C, 0 °C, +1 °C, and –7 °C. What was the mean daily low temperature for those 4 days?
4. The temperature of a new freezer, before it is plugged in, is 22 °C. When it is plugged in, the temperature drops to –10 °C.
a) Find the temperature change. Start temperature of 22 °C = ( ) End temperature of –10 °C = ( ) Temperature change = end temperature – start temperature Sentence: _________________________________________________________________ b) When the freezer is plugged in, the temperature inside drops by 4 °C per hour. How many hours does it take for the freezer to reach –10 °C?
Temperature drop of 4 °C = (– )
Number of hours = temperature change ÷ temperature drop Sentence: _________________________________________________________________
5. The daily low temperatures in Prince Rupert, British Columbia, were –4 °C, +1 °C, –2 °C, +1 °C, and –6 °C. What is the mean temperature?
Add the integers.
Divide by the number of days. ÷ = The mean of the daily low temperatures was °C. 6. Earth’s surface temperature is 15 °C. The temperature increases by 25 °C for each kilometre you travel below Earth’s surface.
a) What is the temperature increase 1 km below the surface?
Sentence: _________________________________________________________________ b) How much would you expect the temperature to increase 3 km below the surface? 3 km = ( ) 25 °C/km = (+ ) × = Sentence: _________________________________________________________________
Sports Link The running event in the pentathlon is a 3000-m cross-country race.
pentathlon • a sports event that includes shooting, fencing, swimming, horse jumping, and running
A male athlete scores 1000 points for finishing in 10 min. A female athlete scores 1000 points for finishing in 11 min 20 s. Each whole second under these times is worth 4 extra points. Each whole second over these times is worth a loss of 4 points. Show how to calculate the points earned by each athlete.
a) male: 920 points in 10 min 20 s
How much over time is he? Lost points = (seconds over 10 min) × 4 = × = Original points – lost points = – = 920
b) female: 1060 points in 11 min 5 s How much under time is she? Extra points = (seconds under 11 min 20s) × 4 = × = Original points + gained points = + =
c) Calculate the points earned by a female athlete with a time of 11 min 43 s. How much over time is she? s Find the total points lost: Original points – lost points = – = The athlete earned points.
8 Chapter Review Key Words For #1 to # 5, use the word list to complete each statement.
zero brackets product zero pair quotient 1. Integers include positive and negative whole numbers and . 2. To find the answer for –2 + (4 – 9) ÷ 5 × 3, do first. 3. An integer chip for +1 and an integer chip for –1 are together called a . 4. To find the means you multiply. 5. When (–10) is divided by (+5), the is (–2). 8.1 Exploring Integer Multiplication, pages 416–422 6. Write the multiplication statement for each diagram.
a)
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( ) × ( ) =
b)
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+ + + + + + +
( ) × ( ) =
7. Find the product. Draw integer chips to show your thinking.
8. A sloth took 9 min to climb down a tree. He moved down 2 m/min. How far did the sloth climb down? Total time = ( ) Distance for 1 min = ( ) ( ) × ( ) = The sloth climbed down m in 9 min. 8.2 Multiplying Integers, pages 424–428 9. Find the product using a number line.
a) (–4) – (–10) ÷ (–5) = Divide. = (–4) + (+ ) Add the opposite. =
b) 12 ÷ [(– 4) + (–2)] Brackets. Divide.
18. A small plane descended 90 m at 3 m/s.
Then it descended 80 m at 2 m/s. For how much time did it descend altogether? 90 m at 3 m/s: Descending 90 m = (– ) Number of m/s = ( )
80 m at 2 m/s: Descending 80 m = (– ) Number of m/s = ( )
Time descending at 3 m/s + time descending at 2 m/s = (–90) ÷ ( ) + (–80) ÷ ( ) Divide first. = + Add. = Sentence: ____________________________________________________________________
19. The daily low temperatures in Winnipeg, Manitoba were –2 °C, +3° C, –4 °C, and –5 °C. What was the mean temperature? Add the temperatures:
Short Answer 7. Model (–12) ÷ (+3) on the number line.
�15 �14 �13 �12 �11 �10 �9 �8 �7 �6 �5 �4 �3 �2 �1 0 �5�1 �2 �3 �4 8. Model (–2) × (+5) using integer chips. 9. Solve. Use the sign rule.
a) (–6) × (+8) = b) (–5) × (–9) =
c) (–64) ÷ (–8) = d) (+99) ÷ (–11) =
10. The daily high temperatures for 4 days in Whitehorse, Yukon Territory, were +1 °C, –1 °C, –2 °C, and –6 °C.
What was the mean daily high temperature for those 4 days? Sentence: ____________________________________________________________________ 11. Write a word problem that you could solve using the expression (+4) × (–8).
How does the air temperature change as it travels from Vancouver Island, over the mountains, and to Calgary? • air temperature is 18 °C on Vancouver Island • air rises 4 km to get over the mountains • for the first 1 km of the climb, the air cools by 10 °C/km
a) What is the temperature 1 km above Vancouver Island? (+18) + (–10) = °C Fill in #1 on the diagram. b) After the first 1 km of the climb, the air cools at 5 °C/km. What is the temperature at the top of the mountains (4 km)? At 1 km from Vancouver Island, the temperature dropped °C. The next 3 km to the top of the mountains, the temperature dropped °C
for each km. Temperature at the top of mountains = (+18) + (–10) + (–5) + (–5) + (–5) = Fill in #2 on the diagram. c) As the air descends 3 km to Calgary, the temperature rises at a rate of 10 °C/km. What is the temperature of the air when it reaches Calgary? Temperature at top + total temperature increase down the mountains = + =
Sentence: __________________________________________________________________ Fill in #3 on the diagram.
integer chips zero pair negative positive integer sign rule number line multiply divide product quotient numerals order brackets operations
N U M B E R L I N E O T E S G F T W R N L D V Q F A Y J V B N P P L L M F B E C J X Y T V L T K W E S I E H U A Q G W T I Z F Q A Y O C I C H Y M R U R A G P R L V J Z X K G T Y C Z L O G A T N M U I I C L S P Q O H R C E P X N I T I G D O N Q I Q W U K E C D R I B V S M I F I J T R M Z Q A G W O C O T E B W I Q O Z S E W O P P E R B I R P L Y J N A M E N C G P D H T R I R T E A U B K Z I L Y L S E Y Q N N V V E I A I M M R T M L B T J R H I E Q O M O B V R I J P A G Z Q N Z U P U U X Z N D M W N M O E A C W W H Y M E A Z W N P M C I F P X G T O K G H O T F Z X N T G S M R R Z P Z X D Y E P N D N U M E R A L S O E O E S X K K X T H E V I T I S O P D S H D C G N D X Z Y S G R R H H S G U O Q F L R K E U E V F A E D I V I D C C U O L J L O H M W C B G L B K Q K T D R T N V S N Y L I R S U M
Use a key word to fill in the blanks. 1. The answer to a multiplication question is called a . 2. The order of is when you complete the brackets first, then multiply
or divide in order, and then add or subtract in order. 3. A positive integer chip and a negative integer chip make a . 4. When you 2 numbers, you find the quotient. 5. 0, +7, and –10 are each an .
Integer Race Play Integer Race with a partner or in a small group.
• hundred chart for each pair
or group of students • 2 dice for each pair or group
of students • counter per student
Rules
• To decide who goes first, each player rolls 1 die. The highest roll goes first. If there is a tie, roll again. • For each turn, roll both dice. • Rolling a 1, 2, or 3 gives a negative value.
• Rolling a 4, 5, or 6 gives a positive value. Scoring
• Multiply the numbers on the dice. • A player must score a positive answer to start the game. • After a player’s first positive score, the player puts a
counter on the score on the grid.
• Players use their scores to move the counter to a higher or lower square on the chart.
• The first player to reach square 100 is the winner.
+ integers are for money you make – integers are for money you spend
Challenge in Real Life
Running a Small Business You be the small business owner! You own a games store. You have to keep track of your money. The tables show information about some of the games in your store.
You buy games from a supplier at 1 price. You sell games to customers at a higher price.
Game Price Integer
Game X $10 Buy from Supplier Game Y $ 6
Game Price Integer
Game X $15 Sell to Customers Game Y $11
1. Complete the tables by writing an integer for each price. 2. Use multiplication or division statements
to solve the problems.
a) You buy 12 copies of Game Y from the supplier. 12 copies = Price of Game Y is $ = ( ) × ( ) = It costs $ to buy 12 games.
b) You sell 3 copies of Game Y to customers. Sentence: _________________________________________________________________ c) A customer returns 2 copies of Game X for a refund. Sentence: _________________________________________________________________
Chapters 5—8 Review Chapter 5 1. Draw the top, front, and side views.
a) top front side
b) top front side
2. Draw a net on the grid for a right rectangular prism with • length = 6 units • width = 3 units • height = 4 units 3. A can of beans has a diameter of 10 cm and is 14 cm high. Find the surface area of the can. d = r = h = Formula → S.A. = 2 × (π × r2) + (π × d × h)
4. Cho and her dad are building a skateboard ramp.
a) Using the picture of the ramp, write the dimensions on each diagram.
1 m
m
end
m
m
sides
m
1.2 m
base
m
m
top
b) How much plywood will they need to make the whole ramp?
Sentence: ________________________________________________________________ Chapter 6 Fraction Operations 5. The incubation time for a pigeon is 18 days.
6. Mei can usually drive home at an average speed of 60 km/h. Because of a storm, Mei slows down so that her average speed was two thirds her normal speed.
What was her average speed that day? Sentence: ____________________________________________________________________ 7. At the end of a party, half of a cake is left. Five people share the leftover cake equally. What fraction of cake does each person get?
Chapter 7 Volume 9. Find the volume of oil that can be stored in this container. Formula → V = π × r
2 × h V = π × r × r × h Substitute → V = × × × Solve → The volume of oil that can fit into this container is . 10. Jojo’s waterbed mattress is in the shape of a rectangular prism.
It is 2.5 m long, 1.5 m wide, and 0.2 m in height. What volume of water is in the mattress when it is filled? Formula → Substitute → Solve →
Sentence: ____________________________________________________________________ 11. Pop cans are often sold in cases of 12.
a) Find the volume of 1 can of pop. Formula → Substitute → Solve →
b) Find the volume of 12 cans of pop. Volume of 1 can of pop:
12. A solid cube has a side length of 10 cm. A cylindrical section with a radius of 3 cm is removed from the cube.
a) Find the volume of the cube before the cylinder is removed. Formula → Substitute → Solve → Sentence: _________________________________________________________________ b) Find the volume of the cylindrical section. Formula → Substitute → Solve → Sentence: _________________________________________________________________ c) Find the remaining volume after the cylindrical section is removed. Remaining volume = area of cube – area of cylinder Sentence: _________________________________________________________________
a) (+22) × (–14) Estimate: Calculate: × = (+22) × (–14) = b) (46) × (–13)
15. The temperature in Inuvik, Northwest Territories, increased at a steady rate from –22 °C at 9:00 a.m. to –8 °C at 4:00 p.m. a) What was the temperature change from 9:00 a.m. to 4:00 p.m.? Sentence: _________________________________________________________________ b) How many hours are between 9:00 a.m. to 4:00 p.m.? c) What was the temperature change per hour?
total temperature changenumber of hours
=
=
16. Calculate using the order of operations. a) –2 × [–6 + (–3)] – 10
_________ × __________ = ___________ _________ ÷ __________ = _________ 3. The answers for Set 1 are between 0 and . 4. The answers for Set 2 are greater than .
470 MHR ● Chapter 8: Integers
Answers Get Ready, pages 412–413
1. a) +3 b) –20 2. a) +3 b) (–3) + (–4) = (–7) 3. a) +9 b) +6 4. a) –4 b) –8 5. a) +37 b) +19 Math Link
a) +5 °C b) –5 °C c)
+ + + + + + + + + + + + +
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+ + + + + + + + +
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d)
�20 �15 �10 �5
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�50
e) +20 °C
f) Answers will vary. Example: I would divide by 4. 8.1 Warm Up, page 415
1. a) +1
b) +1
2. a) –12
b) –2
3. a) –7 b) +8 c) –3 d) +11 4. a) 18 b) 10 c) 6 d) 5 8.1 Exploring Integer Multiplication, pages 416–422
Working Example 1: Show You Know
a) +8
b) –10
c) –8
d) +6
Working Example 2: Show You Know
–8 °C Communicate the Ideas
1. NO. Using 3 positive chips and 7 negative chips would show 3 + (–7). Practise
2. a) (+5) × (+1) b) (+2) × (–6) 3. a) (+8) + (+8) + (+8) b) (–6) + (–6) + (–6) + (–6) + (–6) 4. a) (+2) × (+4) = +8 b) (+4) × (–2) = –8 5. a) +24 b) –14 6. a) –5 b) +16 Apply
7. a) 12 °C b) $32 8. 16 m
9. 36 m 8.2 Warm Up, page 423
1. a) (–4) + (–4) + (–4) + (–4) + (–4) b) (+8) + (+8) + (+8) 2. a) (–2) × (+4) = –8 b) (+2) × (–5) = –10 3. a) +12
+++ + + +
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+ + + +
++
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+ + + +
b) –15
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8.2 Multiplying Integers, pages 424–428
Working Example 1: Show You Know
a) +28 b) –30 c) +16 d) –36 Working Example 2: Show You Know
$1170 Communicate the Ideas
1. Answers may vary. Example: 7 groups of 3 positive chips is +21. 2. YES. Each statement multiplies a positive and a negative, so the product
is negative. Practise
3. a) (+2) × (+4) = +8 b) (+2) × (–6) = –12 4. a) +25 b) –18 5. a) +40 b) –30 c) –35 d) +32 6. Estimates may vary. a) –400; –408 b) 1500; 1316 Apply
7. $180 8. a) +3 b) +5 c) –4 d) –4 9. 1500 m 10. 2400 m Math Link
a) negative b) 1 km: –6 °C, 2 km: –12 °C, 3 km: –18 °C, 4 km: –24 °C, 5 km: –30 °C, 6 km: –36 °C, 11 km: –66 °C c) –62 °C d) 6 km e) increase f) increased by 36 °C 8.3 Warm Up, page 429
1. Estimates may vary. a) –200, –187 b) 600, +588 2. a) –14 b) +30 c) +16 d) –30 e) 0 f) +27 3. a) 2 b) 9 c) 9 d) 5 e) 5 f) 8 4. a) –40 b) +5 c) +2 d) +9 5. a) positive, +28, +28 b) negative, –30, –30 8.3 Exploring Integer Division, pages 430–435
Working Example 1: Show You Know
a) +2
+++ + + + +
+++ + + + +
+++ + + + +
+++ + + + +
b) +3
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Answers ● MHR 471
Working Example 2: Show You Know
4 Communicate the Ideas
1. a) Allison created groups of 6 chips, and counted the number of groups. Tyler created 6 groups of chips and counted the number of chips in a group.
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Practise
2. a) +5 b) +4 c) –7 d) –5 3. a) +7; +2 b) +5; –2 4. a) +4
b) –1
c) +2
d) –5
Apply
5. 7 min 6. a) –18 °C b) 6 h c) –3 °C/h 7. a) +4, +3, +2, +1, 0, –1, –2 b) decreases by 1 8.4 Warm Up, page 436
1. a) Answers will vary. Example: –5, +5 b) same number with opposite signs
2. a) +3 b) –2 3. –2
4. a) 2 b) 3 c) 1 5. a) 4 b) 4 c) 9 d) 4 8.4 Dividing Integers, pages 437–443 Working Example 1: Show You Know a) +3 b) –3 c) +4 d) –6 Working Example 2: Show You Know
$14 Communicate the Ideas
1. a)
�12�10�8 �6 �4 �2
�2 �2 �2�2 �2 �2
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�12 �6
�6 �6
0 c) NO. The number lines are the same, but the sections on the line
showing –12 are different sizes. 2. The numbers are the same in both statements, and both statements have
4. a) +2 b) +5 c) –2 d) +2 5. a) +4 b) –6 c) –3 d) +2 Apply
6. a) –5 b) +20 c) –2 d) +5 7. 4 months
8. a) 6 m/min b) 8 m/min 9. $12 10. a) Answers will vary. Example: A pumps draws 80 L of water from a
tank in 16 s. How much water is drawn from the tank each second? b) (–80) ÷ (+16) = –5
Math Link
a) –42 °C b) 7 km 8.5 Warm Up, page 444
1. +3
2. a) +4 b) –20 3. a) –3 b) –11 4. a) –12 b) +12 5. a) –21 b) +22 c) –2 d) +8 6. a) 14 b) –2 c) 8 d) 10
8.5 Applying Integer Operations, pages 445–451
Working Example 1: Show You Know
a) +25 b) +6 c) +2 d) –19 e) –5 f) +40 g) –22 Working Example 2: Show You Know
–3 °C Communicate the Ideas
1. a) –15 b) NO c) Lance did not do the brackets first. Practise
2. a) +17 b) –13 3. a) 6 b) –14 c) –10 d) +4 Apply
4. a) 32 °C b) 8 h 5. –2 °C 6. a) 40 °C b) 75 °C Sports Link
a) Lost points: 20 × 4 = 80 b) Extra points: 15 × 4 = 60 c) Lost points: 23 × 4 = 92; Total: 908 Chapter Review, pages 452–455
1. zero 2. brackets 3. zero pair 4. product 5. quotient 6. a) (+2) × (–5) = –10 b) (–4) × (+2) = –8 7. a) +9
b) –20
8. 18 m 9. a) –18 b) +8 10. a) –56 b) +90 11. Estimate may vary. –500; –539 12. a) +5; +2 b) +4; –2 13. a) +7
b) –1
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472 MHR ● Chapter 8: Integers
14. +6
15. a) +3 b) –8 c) –17 d) +8 16. $18 17. a) –6 b) –2 18. 70 s 19. –2 °C Practice Test, pages 456–457
1. C 2. D 3. B 4. D 5. B 6. A 7.
�12�9 �6 �3 0
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9. a) –48 b) +45 c) +8 d) –9 10. –2 °C 11. Answers will vary. Example: Brianna repaid Carrie $8 a week for 4
weeks. How much money did Brianna repay? Wrap It Up!, page 458
a) +8 °C b) –7 °C c) 23 °C Key Word Builder, page 459
1. product 2. operations 3. zero pair 4. divide 5. integer Challenge in Real Life, page 461
Game Price Integer Game X $10 –10
1. Buy from
Supplier Game Y $6 –6
2. a) $72 b) $33 c) $30 3. 24 4. Answers will vary. Example:
Day of the Week
Buy from Supplier
Sell to Customers Refunds
Friday Game X: $100 Game Y: –$90
Game X: $120 Game Y: $121
Game X: –$30 Game Y: –$44
Saturday Game X: –$150 Game Y: –$90
Game X: $180 Game Y: $132
Game X: –$45 Game Y: 0
Return to Supplier
Amount of Money Out
Amount of Money In
Game X: $20 Game Y: $30
Game X: –$130 Game Y: –$134
Game X: $140 Game Y: $151
Game X: $30 Game Y: $18
Game X: –$195 Game Y: –$90
Game X: $210 Game Y: $150
Game Price Integer Game X $15 +15 Sell to
Customers Game Y $11 +11
Chapter 5–8 Review, pages 463–468
1. a) b) 2.
3. 596.6 cm2 4. a)
b) 8.24 m2 5. 21 days 6. 40 km/h
7. 110 of the cake
8. 54 cm 9. 0.19625 m3
10. 0.75 m3 11. a) 385.84 cm3 b) 4630.12 cm3 12. a) 1000 cm3 b) 282.6 cm3 c) 717.4 cm3 13. a) +3 b) –9 c) –6 d) –3 14. a) –200; –308 b) –500; –598 15. a) 14 °C b) 7 h c) 2 °C/h 16. a) 8 b) –10 Task, page 469