Why must m in the equation ymx b always be a positive number?

In the equation ( y = mx + b ), where ( m ) represents the slope, it is not a requirement for ( m ) to always be a positive number. The sign of ( m ) indicates the direction of the line: a positive ( m ) means the line slopes upward, while a negative ( m ) indicates a downward slope. Therefore, ( m ) can be positive, negative, or zero depending on the relationship between the variables being graphed.