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:
- [latex]-9\cdot 3[/latex]
- [latex]-2\left(-5\right)[/latex]
- [latex]4\left(-8\right)[/latex]
- [latex]7\cdot 6[/latex]
Solution:
1. |
|
|
[latex]-9\cdot 3[/latex] |
Multiply, noting that the signs are different and so the product is negative. |
[latex]-27[/latex] |
2. |
|
|
[latex]-2\left(-5\right)[/latex] |
Multiply, noting that the signs are the same and so the product is positive. |
[latex]10[/latex] |
3. |
|
|
[latex]4\left(-8\right)[/latex] |
Multiply, noting that the signs are different and so the product is negative. |
[latex]-32[/latex] |
4. |
|
|
[latex]7\cdot 6[/latex] |
The signs are the same, so the product is positive. |
[latex]42[/latex] |