
(7) (14 pts). Use Cauchy sequence definition to prove {an) = {2:ne N} is a Cauchy...
3n-1 is not Cauchy sequence. 3(-1)*+* 5n-27 2. Problem 2 (10 pts.) Prove that sequence an = (-1)"+1 %3D
Show that the sequence is Cauchy using the definition of Cauchy se- quences. Sn 2n +1 n +4
5. (a) (7 points) Use the definition of convergence to prove that the sequence {(-1)-+ 히 converges to 0 (b) (7 points) Prove that the sequence k=1 does not converge.
4. (20 pts) Let {xn} be a Cauchy sequence. Show that a) (5 pts) {xn} is bounded. Hint: See Lecture 4 notes b) (5 pts) {Jxn} is a Cauchy sequence. Hint: Use the following inequality ||x| - |y|| < |x - y|, for all x, y E R. _ subsequence of {xn} and xn c) (5 pts) If {xnk} is a See Lecture 4 notes. as k - oo, then xn OO as n»oo. Hint: > d) (5 pts) If...
Show that, if an ≥ 0 for all n ∈ N and (an) is a Cauchy
sequence, then (√ an) is also a Cauchy sequence. Hint: x − y = (√ x
− √y)(√ x + √y)
Show that, if an > 0 for all n є N and (an) is a Cauchy sequence, then (Van) is also a Cauchy sequence. Hint: r -y- (V1-vu) (Va + vⓙ
Show that, if an > 0 for all n є N and...
Suppose that a sequence {Zn} satisfies Izn+1-Znl < 2-n for all n e N. Prove that {z.) is Cauchy. Is this result true under the condition Irn +1-Fml < rt Let xi = 1 and xn +1 = (Zn + 1)/3 for all n e N. Find the first five terms in this sequence. Use induction to show that rn > 1/2 for all n and find the limit N. Prove that this sequence is non-increasing, convergent,
1. Prove that if {xn} is a sequence that satisfies 2n² + 3 Xnl73 +5n2 + 3 + 1 for all n e N, then {xn} is Cauchy. . Use the definition of limit for a sequence to show that 2. Suppose that {Xn} converges to 1 as n xn +1-e, as nº n
Show that if an and bn are Cauchy sequences then anbn is a Cauchy sequence. Note that you are not allowed to use convergence, but you can use the definition and the fact that Cauchy sequences are bounded.
#2. Let n E N and X1,X2, ,yn, and zi,22, An be real numbers. ,An, yī,Y2, #a) Prove the identity #b) Use the identity in #a) to prove (the Cauchy-Schwartz inequality) that #1) Extend the result in #b) to prove that #d) Use the inequality in #b) to prove the inequality which is the triangle inequality
#2. Let n E N and X1,X2, ,yn, and zi,22, An be real numbers. ,An, yī,Y2, #a) Prove the identity #b) Use the identity...
(1). Let {?n} be a Cauchy sequence in a metric spaces X and let {?n} be another sequence in X such that ? (?n, ?n) < 1/n ??? ????? ? ∈ ℕ. Show that {?n} is also a Cauchy sequence in X.