f(x)=x^3-2
df(x)=3*x^2
xi=2^(1/3)
x0=1

lambda=0.02
g(x)=x-lambda*f(x)

xn=x0
for n=1:170
	global xn
	xn=g(xn)
	println("n=$n xn=$xn en=$(xn-xi)")
end