Symmetry about the x-axis is (x,y) to (x,-y) so when you plug in -y the equation will stay the same if symmetrical, For y-axis (x,y) to (-x,y) plug in -x, For the line y=x (x,y) to (y,x) so plug in y for x and x for y, For the origin (x,y) to (-x,-y) plug in -x and -y