Writing the Equation of a Line To write the equation of a line, you must know the slope, m, and the y-intercept, b. If it is in the form of y =mx + b, you have both the slope and the y-intercept. If it is not in slope-intercept form, you need solve for y in order to find m and b.
Graphing Lines Plot the y-intercept on the y-axis. Obtain a second point by using the slope, starting from the y-intercept. If the slope is positive go up if it is negative go down, going the same number of spaces as the top number. Then go to the right or positive direction the same number of spaces as the bottom number. Use a straightedge to connect the dots. Remember – A line continues infinitely in both directions, so put arrows on the end of your lines.