1. Adding Real Numbers Find each sum. 1. 4 + 2 2. 10 + 7 3. 9 + 5
ALGEBRA 1 LESSON 1-4
(For help, go to skills handbook page 726.)
Find each sum. 1 5 3 4 9 7 2 8
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2. Adding Real Numbers Solutions 1. 4 + 2 = 6 2. 10 + 7 = 17
ALGEBRA 1 LESSON 1-4
= = 17
= = 59
= = 5.2
= 10.9
= 17.1
= =
= = = 1
= = = = 1
= = = 1 5 3
1 + 3 4 9 7
4 + 7 11 2
2 + 3 8
3 + 2
Solutions
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3. Adding Real Numbers Use a number line to simplify each expression.
ALGEBRA 1 LESSON 1-4
Use a number line to simplify each expression.
Use a number line to simplify each expression.
a. 3 + (–5)
b. –3 + 5
Start at 3.
Move left 5 units.
Start at –3.
Move right 5 units.
3 + (–5) = –2
–3 + 5 = 2
c. –3 + (–5)
Start at –3.
Move left 5 units.
–3 + (–5) = –8
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4. Adding Real Numbers Simplify each expression. a. 12 + (–23) = –11
ALGEBRA 1 LESSON 1-4
Simplify each expression.
a (–23) = –11
b. –6.4 + (–8.6) = –15.0
The difference of the absolute values is 11.
Since both addends are negative, add their absolute values.
The negative addend has the greater absolute value, so the sum is negative.
The sum is negative.
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5. Adding Real Numbers
ALGEBRA 1 LESSON 1-4
The water level in a lake rose 6 inches and then fell 11 inches. Write an addition statement to find the total change in water level.
6 + (–11) = –5   The water level fell 5 inches.
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6. Adding Real Numbers Evaluate 3.6 + (–t) for t = –1.7.
ALGEBRA 1 LESSON 1-4
Evaluate (–t) for t = –1.7.
3.6 + (–t) = [–(–1.7)] Substitute –1.7 for t.
= [1.7] –(–1.7) means the opposite of –1.7, which is 1.7.
= 5.3 Simplify.
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7. Adding Real Numbers
ALGEBRA 1 LESSON 1-4
A scuba diver who is 88 ft below sea level begins to ascend to the surface.
a.  Write an expression to represent the diver’s depth below sea level after rising any number of feet.
Relate: 88 ft below sea level plus  feet diver rises  
Define: Let r = the number of feet the diver rises.
Write: –88 + r
–88 + r
b.  Find the new depth of the scuba diver after rising 37 ft.
–88 + r = – Substitute 37 for r.
= – 51 Simplify.
The scuba diver is 51 ft below sea level.
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8. Adding Real Numbers 7 –5.4 –2 11.1 3 –1 –6 8.6 11 2.3 5 –3 Add +
ALGEBRA 1 LESSON 1-4
7 –5.4 –2 –1 –
2.3 5 –3
Add +
7 –5.4 –2 –1 – –3 +
– (–5.4) 11 + (–2)
–3 + (–1)
Add corresponding elements. = –4
Simplify. =
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9. Adding Real Numbers Simplify.
ALGEBRA 1 LESSON 1-4
Simplify.
(– 10) 2. – 57 + (– 11) 3. –
4. – (– ) 5.
6. Evaluate x for x = – 5. 5
–68
–23 1 5 4 15
3 –5
–2 0
–2 –4
8 –6 +
1 – 9
6 – 6 –4 7 15 5
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