I see an equation which is being graphed and perhaps you are seeing only the final form of the equation above the graph.  The simplification steps are shown below the graph and it is typically best to start with 'a few steps' and only add additional solution steps when the extra information is helpful rather than confusing.  A specific solution step can be clicked on in order to review the logic which was employed. 

For any graphable equation, the software first manipulates it into its standard form before graphing; for a linear equation, that form is "y=mx+b" where the slope "m" may then be determined by inspecting the equation (for example, in the equation "y=-2x+4" "-2" is the correct value for "m"). For a parabolic equation, the standard form is y = a(x - h)^2 + k, from which direction (polarity of "a") and axis of symmetry (value of "h"), etc. may be determined by inspection.