Before we begin graphing systems of equations, a good starting point is to review our knowledge of 2-D graphs. These graphs are known as 2-D because they have two axes. Find an online image of a graph to use as the foundation of your discussion. (This is easily accomplished by searching within Google Images.)
Using your graph as the example:
Select any two points on the graph and apply the slope formula, interpreting the result as a rate of change (units of measurement required); and
Use rate of change (slope) to explain why your graph is linear (constant slope) or not linear (changing slopes).
Embed the graph into the post by copying and pasting into the discussion. You must cite the source of the image. Also be sure to show the computations used to determine slope.