If P_{1}(x_{1}, y_{1})and P_{2}(x_{2}, y_{2})are two different points, then the slope of the line between them is;

If the slope of a line is zero (0) then the line is a horizontal line.

If the slope of a line is undefined, then the line is a vertical line.

ex.

Find the slope of the line, m, between A(-3,1) and B(4,6)