The slope of a line can be positive, negative, zero, or undefined. Below are graphical representations of a positive, negative, zero, and undefined slope.

Positive Slope
A line rising from the left to right
Negative Slope
Line slanting down from upper left to lower right
Zero Slope
horizontal line
Undefined Slope
vertical line

Deciphering the difference between zero, undefined, and no slopes lines can be difficult. Remember, mathematics is like learning another language.

Interactive exercise. Assistance may be required. Click on the chart below next to the given slope to translate each phrase. Use the slope and the translation to decide which is the correct real world example in the third column.