Manipulate[Show[ParametricPlot[{2,3}+t{1,-1},{t,-4,4},AxesOrigin->{0,0}],Graphics[Arrow[{{0,0},{2,3}+s{1,-1}}]]],{s,-4,4}]

Plot3D[3x+4y,{x,-1,1},{y,-1,1}]

ContourPlot3D[2x+y-z==1,{x,-4,4},{y,-4,4},{z,-4,4},AxesLabel->{x,y,z}]