Multiplication of Signed Numbers
The sign of the product of two numbers depends on their signs.
Same signs |
Product |
•Two positives
•Two negatives |
Positive
Positive |
Different signs |
Product |
•Positive • negative
•Negative • positive |
Negative
Negative |
example
Multiply each of the following:
- −9⋅3
- −2(−5)
- 4(−8)
- 7⋅6
Solution:
1. |
|
|
−9⋅3 |
Multiply, noting that the signs are different and so the product is negative. |
−27 |
2. |
|
|
−2(−5) |
Multiply, noting that the signs are the same and so the product is positive. |
10 |
3. |
|
|
4(−8) |
Multiply, noting that the signs are different and so the product is negative. |
−32 |
4. |
|
|
7⋅6 |
The signs are the same, so the product is positive. |
42 |