ContourPlot[{x==y,x==-y,(Sqrt[(x^2)-(y^2)])==1,(Sqrt[(x^2)-(y^2)])==2},{x,-3,3},{y,-3,3},PlotTheme->"Monochrome",ContourStyle->Dashing[None],AxesLabel->{x,y},Axes->True,AxesStyle->Arrowheads[0.05],LabelStyle->Larger,Frame->False]

Export["/homes/bradfoa/Documents/261/Quizzes/Quiz 3/contours.pdf",%23,"PDF"]