documentclass[tikz,border=3.14mm]{standalone}
begin{document}
begin{tikzpicture}[pics/symmetric axes/.style={code={
draw[thick,-stealth] (0,-#1) -- (0,#1);
draw[thick,-stealth] (-#1,0) -- (#1,0);}},pics/symmetric axes/.default=5]

 pic{symmetric axes};
 draw[red,thick] plot[variable=x,domain=-4:4,smooth] ({x},{2*tanh(x)+0.5*x});

 begin{scope}[xshift=7cm]
  pic{symmetric axes};
  draw[red,thick] plot[variable=x,domain=-4:4,smooth] ({pow(x,3)/8-x},{x});
 end{scope}
end{tikzpicture}
end{document}