Let (X, d) be a metric space. Show that every Cauchy sequence {x_n} X is bounded. Solution we need to prove that every cauchy sequence {xn} in metrix space {X,d} is bounded. let assume that xn be a Cauchy sequence of (X, d) hence we can say that by definition of cauchy sequence = 1 so we can say that there exists N such that, d(xm , xn) < 1 for all m, n N hence we can say that xn B(xN , 1) for all n N now r = 1 + max{1, d(x1, xN), d(x2, xN), . . . , d(xN-1, xN)} we can see that, xn B(xN ; r) for all n so we can say that xn is bounded..