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.  Your equation was provided in 'standard form' and hence no algebraic manipulation would be useful.  Note that 'a' is '-1', 'h' is '1' and 'k' is '3'. 

Your inequality defines a parabolic region and any values lying within that region are 'valid" and any values lying outside of that region are "invalid".  Since "less than or equal" is used, all values lying on that line are "valid", otherwise the graph would show a 'dotted line' defining a "open interval".