What Have We Discussed

1. Negative numbers are useful in real life to represent concepts like financial loss (debt), temperatures below freezing (0°C), past events, and locations below sea level.

2. Integers include all positive numbers (1, 2, 3, ...), all negative numbers (-1, -2, -3, ...), and zero. This complete set of numbers is represented by the letter .

So, Z = {..., -3, -2, -1, 0, 1, 2, 3, ...}.

3. The number line helps us visually understand how are added and subtracted.

4. When two positive numbers are added, the result is always a positive number. Example: 3 + 4 = .

5. When two negative numbers are added, the sum is always negative. Example: (-2) + (-5) = .

6. When adding a positive number and a negative number, we subtract their absolute values and assign the sign of the larger number. Example: 5 + (-3) = , and (-6) + 4 = .

7. Subtracting integers is similar to adding their opposite (additive inverse). Example: 6 - (-3) = 6 + 3 = .