kill(all);

van=facebook.com/LearningCalculus$

f(x):=sqrt(3-x)-sqrt(x+1)-1/2 ;

newton(t):=float(subst(t,x,x-f(x)/diff(f(x),x)));

newton(1/3);

newton(newton(%));

newton(newton(newton(%)));

newton(newton(newton(newton(%))));