2-2 Adding Integers
Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
2-2 Adding Integers
Warm Up
Find each absolute value.
1. |8| 8
2. |–6| 6
3. |–9| 9
4. |–7| 7
5. |–12| 12
6. |53| 53
2-2 Adding Integers
I will…
Learn to add integers.
2-2 Adding Integers
Example 1: Modeling Integer Addition
A. Use a number line to find each sum.
–7 + (–4)
–14
–12
–7
+(–4)
–10
–8
–6
–4
–2
0
2
Start at 0. Move left 7 spaces. Then move left
4 more spaces.
–7 + (–4) = –11
2-2 Adding Integers
Practice 1
B. Use a number line to find each sum.
–12 + 19
19
–12
–12
–10
–8
–6
–4
–2
0
2
4
6
Start at 0. Move left 12 spaces. Then move
right 19 spaces.
–12 + 19 = 7
8
2-2 Adding Integers
Practice 1
C. Use a number line to find each sum.
–4 + (–5)
–14
–12 –10
–4
+(–5)
–8
–6
–4
–2
0
2
Start at 0. Move left 4 spaces. Then move left
5 more spaces.
–4 + (–5) = –9
2-2 Adding Integers
Practice 1
D. Use a number line to find each sum.
–7 + 12
12
–7
–12
–10
–8
–6
–4
–2
0
2
4
6
Start at 0. Move left 7 spaces. Then move
right 12 spaces.
–7 + 12 = 5
8
2-2 Adding Integers
Adding Integers
To add two integers with the same sign,
find the sum of their absolute values. Use the
sign of the two integers.
To add two integers with different
signs, find the difference of their absolute
values. Use the sign of the integer with the
greater absolute value.
2-2 Adding Integers
Example 2: Adding Integers Using Absolute Values
A. Find each sum.
–4 + 8
The signs are different. Find the difference
of the absolute values.
–4 + 8
4
Think: 8 – 4 = 4.
Use the sign of the
integer with the
greater absolute
value.
2-2 Adding Integers
Practice 2
B. Find each sum.
23 + (–35)
The signs are different. Find the difference of
the absolute values.
23 + (–35)
–12
Think: 35 – 23 = 12.
Use the sign of the integer with the
greater absolute value.
2-2 Adding Integers
Practice 2
C. Find each sum.
–5 + 3
The signs are different. Find the difference of
the absolute values.
–5 + 3
–2
Think: 5 – 3 = 2.
Use the sign of the
integer with the
greater absolute
value.
2-2 Adding Integers
Practice 2
D. Find each sum.
–13 + (–24)
The signs are the same. Find the sum of the
absolute values.
–13 + (–24) Think: 13 + 24 = 37.
–37
Use the sign of the two integers.
2-2 Adding Integers
Example 3: Evaluating Expressions with Integers
A. Evaluate x + y for x = –42, y = 71.
x+y
–42 + 71
29
Substitute for x and y.
The signs are different. Think
71- 42 = 29
Use the sign of the integer with the
greater absolute value (positive).
Helpful Hint
When adding integers, think: if the signs are
the same, find the sum. If the signs are
different, find the difference.
2-2 Adding Integers
Practice 3
B. Evaluate x + y for x = –24, y = 17.
x+y
–24 + 17
–7
Substitute for x and y.
The signs are different.
Think: 24 – 17 = 7.
Use the sign of the integer with the
greater absolute value (negative).
2-2 Adding Integers
End Day #1
2-2 Adding Integers
Day #2
2-2 Adding Integers
Problem of the Day
Jan’s yearly salary is $30,000, and it will
be increased by $3,000 each year. Phil’s
salary is $20,000, and it will be
increased by $5,000 each year. In how
many years will Jan and Phil both have
the same yearly salary?
5 years
2-2 Adding Integers
Example 4: Application
A. The jazz band’s income from a bake sale
was $286. Expenses were $21. Use integer
addition to find the band’s total profit or loss.
286 + (–21)
286 – 21
265
Use negative for the expenses.
Find the difference of the
absolute values.
The answer is positive.
The band earned $265.
2-2 Adding Integers
Practice 4
B. The French Club was raising money for a
trip to Washington D.C. Their car wash raised
$730. They had expenses of $52. Use integer
addition to find the club’s total profit or loss.
730 + (–52)
730 – 52
678
Use negative for the expenses.
Find the difference of the
absolute values.
The answer is positive.
The club earned $678.
2-1 Integers
Lesson
Quiz
2-2 Adding Integers
Use a number line to find the sum.
1. –7 + (–6)
Find each sum.
2. –15 + 24 + (–9)
3. –24 + 7 + (–3)
4. Evaluate x + y for x = –2 and y = –15.
5. The math club’s income from a bake sale was
$217. Advertising expenses were $32. Use integer
addition to find the club’s total profit or loss?
2-2 Adding Integers
Lesson Quiz
ANSWERS: Part I
Use a number line to find the sum.
1. –7 + (–6)
–13
6 units
–14
–12
–10
7 units
–8
–6
–4
–2
0
2
Find each sum.
2. –15 + 24 + (–9)
3. –24 + 7 + (–3)
0
–20
4. Evaluate x + y for x = –2 and y = –15.
–17
2-2 Adding Integers
Lesson Quiz
ANSWERS: Part 2
5. The math club’s income from a bake sale was
$217. Advertising expenses were $32. Use
integer addition to find the club’s total profit or
loss?
$185 profit