Linear Functions

Rate that describes how one quantity changes in relation to another quantity

If x is the independent variable and y is the dependent variable, then. rate of change=change in y change in x

A positive slope means the line is increasing when viewed from left to right.


As you can see, Mr. Piggy is having a hard time going up since it costs him an extra effort for an uphill climb.

A negative slope means the line is decreasing when viewed from left to right.

Thanks to gravity, Mr. Piggy is definitely enjoying the slide because it takes him less effort to go down.

A zero slope means the line is neither increasing nor decreasing when viewed from left to right, or vice versa. 

Simply put, the slope of a horizontal line is zero,

An undefined slope or infinite slope, means the line is neither moving to the left nor to the right such as the case of a vertical line. The slope of a vertical line is either + \,\infty+∞ or - \,\infty−∞.