ContourPlot[{y^2==x^3-0x^2 -5x + 6},{x,-5,5},{y,-10,10},Axes->True,Frame->False,Ticks->False]

Graphics[{PointSize[Large],Black,Point[{-2.5,-1.7}],Point[{.5,1.9}],Point[{3.4375,5.425}],Point[{3.4375,-5.425}],FontStyle->"Arial",Style[Text["P",{-2.9,-1.5}],Black,15],Style[Text["Q",{.5,2.75}],Black,15],Style[Text["R'",{3.1, 5.8}],Black,15],
Style[Text["R",{3.1, -5.45}],Black,15]}]

Show[%17,%31]

ParametricPlot[{t,1.2*(t) + 1.3},{t,-3,4},Axes->False,Ticks->False]

Show[%32,%35]

Graphics[{Dashed,Line[{{3.4375,-6},{3.4375,6}}]}]

Show[%36,%37]

Export["addlaw.eps",%]