- 1). Write out a generic linear equation in the form of y = mx + b. This is the form of linear equation most often used to describe a straight-line relationship between two variables. It is possible to write this equation in other ways, for example x = (y - b)/m, but this is the most convenient form of the equation.
- 2). Substitute your numerical value for the slope of the line in place of the variable "m" in the equation. The slope of the line is a measure of its incline and is equal to the distance the line rises vertically over a unit of horizontal distance. If your line slope was 6/1, you would write y = 6x + b.
- 3). Substitute your y-intercept value in place of the variable "b" in the equation. The y-intercept for a line is the point on the vertical y-axis, at x equal to zero, where the line passes through that axis. You now have a complete equation for the straight line that has your particular slope and y-intercept. If your y-intercept was 4, you would write y = 6x + 4. This equation describes the relationship between x and y at all points along the line.
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