% this program plots a parametric curve (r(x),s(x)), where -1<x<3

% keep in mind that this is *not* the solution in Ex 3.7.5, you will have to
% modify the expressions of r and s according to your calculations.

x = linspace(-1,3,1000);
r = (x.^2)./(1+x.^2).^2;
s = (3*x).*(1-x.^2)./(1+x.^2).^2;
plot(r,s);

xlabel(['\bf r'],'fontsize',12)
ylabel(['\bf s'],'fontsize',12)