How to do systems by graphing?

First, get the equation into slope-intercept form: y=mx+b
y=-2x-1
Next, mark the y-intercept on the graph. The y-intercept is b, so in this case it is -1.
Next, go two spaces down on the y-axis, and one space to the right on the x-axis. This is because the slope(m) is -2, which means -2/1. Remember; slope is change in y/change in x, so you will have to use the top number for the number of spaces moved on the y-axis, and the denominator for the number of spaces moved on the x-axis.
You then keep going down two spaces, and one to the right until you have enough points to make a line.
Here is a way to check to see if you made a major error: In slope-intercept form, a negative slope(m) is always a falling line, and a positive slope is always rising. This works until you get into squaring, etc.


This can be done on a TI-84.