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Evaluating Algebraic Expressions 1-4Adding Integers Additional Example 1B: Using a Number Line to Add Integers Use a number line to find the sum. –3 + (–6) –3–6 You finish at –9, so –3 + (–6) = –9. –9 –8 –7 –6 –5 –4 –3 –2 – Start at 0. Move left 3 units. From –3, move left 6 units.
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Evaluating Algebraic Expressions
1-4 Adding Integers
NS1.2 Add, subtract, multiply, and divide rational numbers (integers, fractions, and terminating decimals) and take positive rational numbers to whole-number powers. AF1.3 Simplify numerical expressions by applying properties of rational numbers (e.g. identity, inverse, distributive, associative, commutative) and justify the process used.
California Standards
Evaluating Algebraic Expressions
1-4 Adding Integers
To add a positive number move to the right. To add a negative number move to the left.
Helpful Hint
Additional Example 1A: Using a Number Line to Add Integers
Use a number line to find the sum.(–6) + 2
2–6
You finish at –4, so (–6) + 2 = –4.–6 –5 –4 –3 –2 –1 0 1 2 3 4 5
Start at 0. Move left 6 units. From –6, move right 2 units.
Evaluating Algebraic Expressions
1-4 Adding IntegersAdditional Example 1B: Using a Number Line to
Add IntegersUse a number line to find the sum.–3 + (–6)
–3–6
You finish at –9, so –3 + (–6) = –9.
–9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2
Start at 0. Move left 3 units. From –3, move left 6 units.
Evaluating Algebraic Expressions
1-4 Adding IntegersCheck It Out! Example 1A
Use a number line to find the sum.(–3) + 7
7–3
You finish at 4, so (–3) + 7 = 4.
–6 –5 –4 –3 –2 –1 0 1 2 3 4 5
Start at 0. Move left 3 units. From –3, move right 7 units.
Evaluating Algebraic Expressions
1-4 Adding IntegersCheck It Out! Example 1B
Use a number line to find the sum.(–2) + 4
4–2
You finish at 2, so (–2) + 4 = 2.
–6 –5 –4 –3 –2 –1 0 1 2 3 4 5
Start at 0. Move left 2 units. From –2, move right 4 units.
Evaluating Algebraic Expressions
1-4 Adding Integers
Another way to add integers is to use absolute value.
Evaluating Algebraic Expressions
1-4 Adding IntegersAdditional Example 2: Using Absolute Value to Add
Integers
A. 1 + (–2)
Add.
1 + (–2)2 > 1; use the sign of 2. –1
B. (–8) + 5(–8) + 5
8 > 5; use the sign of 8. –3
Think: Find the difference of 1 and –2 .
Think: Find the difference of –8 and 5 .
Evaluating Algebraic Expressions
1-4 Adding IntegersAdditional Example 2: Using Absolute Value to
Add Integers
C. (–2) + (–4)
Add.
(–2) + (–4)Same sign; use the sign of the integers. –6
Think: Find the sum of –2 and –4 .
Evaluating Algebraic Expressions
1-4 Adding IntegersCheck It Out! Example 2
A. 3 + (–6)
Add.
3 + (–6)6 > 3; use the sign of 6. –3
B. (–4) + 1(–4) + 1
4 > 1; use the sign of 4. –3
Think: Find the difference of 3 and –6 .
Think: Find the difference of –4 and 1 .
Evaluating Algebraic Expressions
1-4 Adding IntegersCheck It Out! Example 2
C. (–6) + (–7)
Add.
(–6) + (–7)Same sign; use the sign of the integers. –13
Think: Find the sum of –6 and –7 .
Evaluating Algebraic Expressions
1-4 Adding IntegersAdditional Example 3: Evaluating Expressions with
Integers
Evaluate c + 4 for c = –8.
c + 4
Replace c with –8.
8 > 4; use the sign of 8.
(–8) + 4
–8 + 4 = –4Think: Find the difference of –8 and 4 .
Evaluating Algebraic Expressions
1-4 Adding IntegersCheck It Out! Example 3
Evaluate d + 7 for d = –3.
d + 7
Replace d with –3.
7 > 3; use the sign of 7.
(–3) + 7
–3 + 7 = 4
Think: Find the difference of –3 and 7 .
Evaluating Algebraic Expressions
1-4 Adding IntegersAdditional Example 4: Application
Meka opened a new bank account. Find her account balance after the first four transactions listed below.Deposits: $200, $20 Withdrawals: $166, $38
Use a positive sign for deposits and a negative sign for withdrawals.
200 + 20 + (–166) + (–38)
Group integers with the same signs.(200 + 20) + (–166 + –38)Add integers within each group.220 + (–204)220 > 204; use the sign of 220.16
Meka’s account balance after the first four transactions is $16.
