Study Guide and Intervention (continued) - MathnMind

2-2
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Study Guide and Intervention
Adding and Subtracting Rational Numbers
Add Rational Numbers
Adding Rational Numbers, Add the numbers. If both are positive, the sum is positive; if both are negative,
Same Sign the sum is negative.
Adding Rational Numbers,
Different Signs
Subtract the number with the lesser absolute value from the number with the
greater absolute value. The sign of the sum is the same as the sign of the number
with the greater absolute value.
Example 1 Use a number line to Example 2
Find each sum.
find the sum 2 (3).
Step 1 Draw an arrow from 0 to 2.
a. 8 5
Step 2 From the tip of the first arrow, draw 8 5 (⏐8⏐ ⏐5⏐)
a second arrow 3 units to the left to
represent adding 3.
Step 3 The second arrow ends at the sum
5. So 2 (3) 5. (8 5)
3
3 1
b. 4 2
Exercises
Find each sum.
3 2
9 8 7 6 5 4 3 2 1 0 1 2 3
1 3 2
⏐ ⏐ ⏐ 3 2
⏐
4
3 2
4 4
1. 12 24 2. 6 14 3. 12 (15)
4. 21.5 34.2 5. 8.2 (3.5) 6. 23.5 (15.2)
7. 90 (105) 8. 108 (62) 9. 84 (90)
2 1
1 7
18 10
13. 14. 15. 3
4
5
11
3 5
16. 17. 1.6 (1.8) 18. 0.008 (0.25)
5 6
© Glencoe/McGraw-Hill 81 Glencoe Algebra 1
3
4
2
4
1 4
5 1
3 6
4 3
10. 11. 12.
7
3
14 17
9 5
40
4
4
20
Lesson 2-2