kill(all)$

van=facebook.com/LearningCalculus$

f(x):= x^x^2-3;

fp(x):=''(diff(f(x),x));

fpp(x):=''(diff(fp(x),x));

fppp(x):=''(diff(fpp(x),x));

newton(t):=float(subst(t,x,x-f(x)/fp(x)))$

newton(newton(newton(newton(newton(1.6)))));