Page 9 - 新思维数学学生用书7 样章
P. 9
1 Integers
1.1 Adding and subtracting integers
In this section you will … Key words
• add and subtract with positive and negative integers. integers
inverse
Integers are positive and negative whole numbers, together with zero. inverse operation
You can show integers on a number line.
negative integers
–6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 number line
Integers greater than zero are positive integers: 1, 2, 3, 4, … positive integers
Integers less than zero are negative integers: −1, −2, −3, −4, …
You can use a number line to help you to add integers.
Tip
The ‘…’ (called
an elipsis) shows
that the lists
continue forever.
Worked example 1.1
Work out:
a −4 + 6 b 8 + −3 c −3 + −5
Answer
a You can use a number line to help you.
Start at −4. Move 6 to the right.
–5 –4 –3 –2 –1 0 1 2 3 4 5 6
−4 + 6 = 2
b Start at 8. Move 3 to the left. You move to the left because it is −3.
–3 –2 –1 0 1 2 3 4 5 6 7 8 9
8 + −3 = 5
c Start at −3. Move 5 to the left.
–8 –7 –6 –5 –4 –3 –2 –1 0 1
−3 + −5 = −8
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