You will need
- Knowledge of analytic geometry. Basic knowledge in algebra.
The equation of the line is given by the coordinates of two points on the plane through which this line must pass. Make a ratio of the coordinates of these points. Let the first point has coordinates (x1,y1) and the second (x2,y2), then the equation of the line is given by: (x-x1)/(x2-x1) = (y-y1)(y2-y1).
Convert the resulting equation of the line and explicitly Express y through x. After this operation, the equation of the line will take its final form: y=(x-x1)/((x2-x1)*(y2-y1))+y1.
If one of the numbers in the denominator equal to zero means that there is a direct parallel to one of the coordinate axes.
After you have compiled the equation of a line, check that it is correct. To do this, substitute the coordinates of the points instead of the corresponding coordinate and verify the validity of the equation.