Figure 1 is an example of a linear equation and its graph.
Figure 1: The linear equation y = 2x - 3 and its graph.
|Standard form||ax + by = c||a, b and c||All lines can be expressed in this form. This form is used in linear systems to make it easier to use matrices.|
|Slope-intercept form||y = mx + b||m is the slope, b is the y-intercept.||Vertical lines can not be expressed in this form, as their slope is undefined.|
|Point-slope form||y = m(x - x0) + y0||m is the slope of the line, (x0,y0) is the coordinate of any point on the line.||This form is useful when the coordinate of a single point on the line is known along with the slope. Vertical lines can not be expressed in this form as their slope is undefined.|
|Two point form||(x1,y1) and (x2,y2) are the coordinates of two distinct points on the line.||This form is useful when the coordinates of any two distinct points of a line are known. Vertical lines can not be expressed in this form as (x2-x1) is 0, and division by zero makes the equation undefined.|
|Vertical line||x = x0||x0 is the x-intercept.||Only vertical lines can be expressed in this form.|
|Horizontal line||y = y0||yo is the y-intercept.||Only horizontal lines can be expressed in this form.|
|Table 1: Forms of linear equations.|
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