1. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
(For help, go to Lessons 1-3 and 1-4)
Find the opposite of each number.
– –
Simplify.
(–2) (–3.5) (–8) –
( ) 7 19 2 3 1 6
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2. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
1. opposite of 6: –6 2. opposite of –7: 7
3. opposite of 3.79: – opposite of – :
(–2) = (–3.5) = 6
(–8) = 5
– = – = = = 7 19 2 3
( ) 1 6 4
4 + (–1)
Solutions
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3. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
Subtract –3 – 2 using a number line.
Start at –3.
Move left 2 units
–3 – 2 = –5
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4. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
Subtract 4 – (–2) using tiles.
Start with 4 positive tiles.
Add zero pairs until there are 2 negative tiles.
Remove 2 negative tiles.
There are 6 positive tiles left.
4 – (–2) = 6
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5. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
Simplify –11.6 – (–14).
–11.6 – (–14) = – The opposite of –14 is 14.
= 2.4 Add.
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6. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
Simplify |–13 – (–21)|.
|–13 – (–21)| = | – |   The opposite of –21 is 21.
= | 8 | Add within absolute value symbols.
= 8 Find the absolute value.
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7. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
Evaluate x – (–y) for x = –3 and y = –6.
x – (–y) = –3 – [–(–6)] Substitute –3 for x and –6 for y.
= –3 – 6 The opposite of –6 is 6.
= –9 Subtract.
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8. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
The temperature in Montreal, Canada, at 6:00 P.M. was –8°C. Find the temperature at 10:00 P.M. if it fell 7°C.
Find the temperature at 10:00 P.M. by subtracting 7°C from the temperature at 6:00 P.M.
–8 – 7 = –8 + (–7) Add the opposite.
= –15 Simplify.
The temperature at 10:00 P.M. was –15°C.
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9. Subtracting Real Numbers
ALGEBRA 1 LESSON 1-5
Simplify each expression.
1. 7 – – (–8) 3. –7 – 5
Evaluate each expression for x = 3 and y = 4.
4. x – y 5. | – y – x| 6. –
– 2 x
y 4
x 8 – 5 y –5 11
–12 –1 7
–5 –5
9 0
1-5