Math Problem Statement

please solve these questions with explanation

Solve questions related to limits, sequences, and series in the provided image, including the Sandwich Theorem and properties of sequences.

Solution

Here are the solutions to the questions in the provided image:


31.

Statement: Poljubna vsota dveh padajočih zaporedij je padajoče zaporedje.
Solution:
This statement is false. Adding two decreasing sequences does not necessarily result in a decreasing sequence. For instance, if the sequences decrease at different rates, their sum may not decrease consistently. Counterexample: an=1/na_n = 1/n, bn=1/n2b_n = -1/n^2. Both are decreasing, but their sum cn=an+bnc_n = a_n + b_n is not decreasing.


32.

Statement: Vsako strogo naraščajoče zaporedje ima limito.
Solution:
This statement is false. A strictly increasing sequence does not always have a finite limit. For example, the sequence an=na_n = n is strictly increasing but diverges to infinity, so it does not have a finite limit.


33.

Statement: Padajoče zaporedje realnih števil je divergentno natanko takrat, ko je navzgor omejeno in navzdol neomejeno.
Solution:
This statement is true. A decreasing sequence of real numbers diverges only when it is bounded above and unbounded below. In this case, it tends to -\infty.


34.

Natančno formuliraj izrek o sendviču.
Solution:
The Sandwich Theorem (Izrek o sendviču) states:
If anbncna_n \leq b_n \leq c_n for all nNn \geq N (for some integer NN), and
limnan=limncn=L,\lim_{n \to \infty} a_n = \lim_{n \to \infty} c_n = L, then
limnbn=L.\lim_{n \to \infty} b_n = L.


35.

Statement: Če je funkcija f:RRf: \mathbb{R} \to \mathbb{R} padajoča, potem obstaja največ eno število, ki je lahko limita rekurzivnega zaporedja x1,x2,x3,x_1, x_2, x_3, \dots, podanega s pravilom xn+1=f(xn)x_{n+1} = f(x_n).
Solution:
This statement is true. If ff is a decreasing function, then it is injective (one-to-one), meaning that the sequence can converge to at most one limit. If a fixed point LL exists such that f(L)=Lf(L) = L, this is the unique limit.


36.

Statement: Če je zaporedje x1,x2,x3,x_1, x_2, x_3, \dots konvergentno in je funkcija f:RRf: \mathbb{R} \to \mathbb{R} odvedljiva, potem je tudi zaporedje f(x1),f(x2),f(x3),f(x_1), f(x_2), f(x_3), \dots konvergentno.
Solution:
This statement is true. If {xn}\{x_n\} converges to LL, and ff is differentiable, then f(xn)f(L)f(x_n) \to f(L) by continuity of differentiable functions. Hence, f(xn)f(x_n) is also convergent.


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5 Related Questions:

  1. What happens when two strictly increasing sequences are added? Is the result always increasing?
  2. Can a bounded, decreasing sequence ever diverge? Why or why not?
  3. How is the Sandwich Theorem applied to prove the convergence of sequences?
  4. What are the implications of a function being injective in the context of recursive sequences?
  5. How does differentiability of a function influence the convergence of related sequences?

Tip:

When analyzing sequences, always check their boundedness and monotonicity; these properties are critical in determining convergence.

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Math Problem Analysis

Mathematical Concepts

Limits
Sequences
Monotonicity
Boundedness
Convergence and Divergence
Fixed Points
Sandwich Theorem

Formulas

If a_n ≤ b_n ≤ c_n for n ≥ N, and lim(a_n) = lim(c_n) = L, then lim(b_n) = L (Sandwich Theorem).
Recursive sequence rule: x_(n+1) = f(x_n).

Theorems

Sandwich Theorem
Convergence of Monotonic Bounded Sequences
Properties of Decreasing and Increasing Functions

Suitable Grade Level

Undergraduate Mathematics