In mathematics, the limit inferior and limit superior of a sequence can be thought of as limiting (i.e., eventual and extreme) bounds on the sequence. They can be thought of in a similar fashion for a function (see limit of a function). For a set, they are the infimum and supremum of the set's limit points, respectively. In general, when there are multiple objects around which a sequence, function, or set accumulates, the inferior and superior limits extract the smallest and largest of them; the type of object and the measure of size is context-dependent, but the notion of extreme limits is invariant.
Limit inferior is also called infimum limit, limit infimum, liminf, inferior limit, lower limit, or inner limit; limit superior is also known as supremum limit, limit supremum, limsup, superior limit, upper limit, or outer limit.
The limit inferior of a sequence
x
n
{\displaystyle x_{n}}
is denoted by
lim inf
n
→
∞
x
n
or
lim
_
n
→
∞
x
n
.
{\displaystyle \liminf _{n\to \infty }x_{n}\quad {\text{or}}\quad \varliminf _{n\to \infty }x_{n}.}
The limit superior of a sequence
Hello everyone, I've been brushing up on some calculus and had some new questions come to mind.
I notice that most proofs of the fundamental theorem of calculus (the one stating the derivative of the accumulation function of f is equal to f itself) only use a limit where the derivative is...
To use the formula above, I have to prove that $$\lim_{n\rightarrow \infty}f(x)=\lim_{n\rightarrow \infty}\left(\frac{1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+........\frac{1}{n}}{n^2}\right)=1$$
To prove so, I tried using L'Hopital's Rule:
$$\lim_{n\rightarrow \infty}f(x)=\lim_{n\rightarrow...
Hi,
I need to check whether the limit of the following function exists or not
I have now proceeded as follows to look at the right-sided and left-sided limit i.e. ##\displaystyle{\lim_{x \to 0^{+}}}## and ##\displaystyle{\lim_{x \to 0^{-}}}##
To do this, I drew up a list in which I move from...
Hi,
I have problems proving task d
I then started with task c and rewrote it as follows ##\lim_{n\to\infty}\sum\limits_{k=0}^{N}\Bigl( \frac{z^k}{k!} - \binom{n}{k} \frac{z^k}{n^k} \Bigr)=0 \quad \rightarrow \quad \lim_{n\to\infty}\sum\limits_{k=0}^{N} \frac{z^k}{k!} =...
## \lim_{x \rightarrow 1} {\frac {x-2} {x^3+ax+b}} = -\infty##
The limit is equal to ##\frac {-1} {1+a+b}## .
so I can say that ## a+b = -1 ##.
But I cannot find another equation to find both ##b-a##.
Since ##\left|3x+2\right|=0\rightarrow\ x=-\frac{2}{3}##, we know the vertical asymptote is at ##x=-\frac{2}{3}##.
Looking at the limit at that point, and also looking at the left- and right-sided limit, I cannot simplify it any further...
My attempt:
(a)
I don't think I completely understand the question. By "evaluate ##\lim_{n\to \infty f_n (x)}##", does the question ask in numerical value or in terms of ##x##?
As ##x## approaches 1 or -1, the value of ##f_n (x)## approaches zero. As ##x## approaches zero, the value of ##f_n...
My attempt:
Since ##\frac{f(a+h)-f(a-h)}{2h}-f'(a)=O(h^2)## as ##h \to 0##, then:
$$\lim_{h \to 0} \frac{\frac{f(a+h)-f(a-h)}{2h}-f'(a)}{h^2} < \infty$$
So
$$\lim_{h \to 0} \frac{\frac{f(a+h)-f(a-h)}{2h}-f'(a)}{h^2} = \lim_{h \to 0} \frac{f'(a)-f'(a)}{h^2}=0 < \infty$$
Because the value of...
This problem builds on my previous post, where we calculated that core's mass is ##M_1=\frac{{v_0}^2r_1}{G}##. So if we consider mass of dark matter dependent on distance ##r## to be ##M_2(r)##, we can calculated it from
##G\frac{(M_2(r)+M_1)m}{r^2}=m\frac{{v_0}^2}{r}.##
So...
Hello. Per what I was taught in my youth, ##\lim_{x \to 0}\frac{1}{x}=\infty##
Is it in agreement with how the calculus is taught today in the High Schools and Universities of US/Canada specifically?
Per what my son says, that limit should be considered as undefined because
##\lim_{x \to...
If ##n## and ##k## are positive integers, let ##S_k(n)## be the sum of ##k##-th powers of the first ##n## natural numbers, i.e., $$S_k(n) = 1^k + 2^k + \cdots + n^k$$ Evaluate the limits $$\lim_{n\to \infty} \frac{S_k(n)}{n^k}$$ and $$\lim_{n\to\infty} \left(\frac{S_k(n)}{n^k} -...
Welcome to this month's math challenge thread!
Rules:
1. You may use google to look for anything except the actual problems themselves (or very close relatives).
2. Do not cite theorems that trivialize the problem you're solving.
3. Have fun!
1. (solved by @AndreasC) I start watching a...
My main question here is about how we actually justify, hopefully fairly rigorously, the steps leading towards converting the sum to an integral.
My work is below:
If we consider the canonical ensemble then, after tracing over the corresponding exponential we get:
$$Z = \sum_{n=0}^\infty...
First i looked at the case of ## \epsilon = 0## and came to the conclusion, that this oscillator has a circular limit cycle in a phase space trajectory, when plotted with the axes x and ##\dot{x}##.
I have found that ##x_0^p (t) = a_1 \cos(t)## which implies that all other Fourier- coefficients...
For this problem,
The limiting position of R is (4,0). However, I am trying to solve this problem using a method that is different to the solutions. So far I have got,
##C_1: (x - 1)^2 + y^2 = 1##
##C_2: x^2 + y^2 = r^2##
To find the equation of PQ,
## P(0,r) ## and ##R(R,0) ##
## y =...
I think that the work is meant to be work done for instance in power stations. Or is it similar to work I do on a body when I lift it for example? But how can we then do that work on our Earth? I just need to understand the task, otherwise I want to solve it myself.
The problem involves...
For this problem,
The solution is,
However, I tried to solve this problem using my Graphics Calculator instead of completing the square. I got the zeros of ##x^2 - 2x - 4## to be ##x_1 = 3.236## and ##x_2 = -1.236##
Therefore ##x_1 ≥ 3.236## and ##x_2 ≥ -1.236##
Since ##x_1 > x_2## then...
This is what I did: $$\lim_ {(x,y) \rightarrow (1,0)} {\frac {g(x)(x-1)^2y}{2(x-1)^4+y^2}}=\lim_ {(x,y) \rightarrow (1,0)} {g(x)y\frac {(x-1)^2}{2(x-1)^4+y^2}}$$ I know that ##\lim_ {(x,y) \rightarrow (1,0)} {g(x)y}=0## and that ##\frac {(x-1)^2}{2(x-1)^4+y^2}## is limited because ##0\leq...
What is the limit of the function as x goes to -5 (e.g. in the graph below) if the domain of the function is only defined on the closed interval [-5,5]?
I realize that the right hand limit DOES exist and is equal to 3, but the left hand limit does not exist?
So does that mean that the overall...
For this problem,
The solution is,
However, when I tried finding the domain myself:
## { x | x - 1 ≥ \sqrt{5}} ## (Sorry, for some reason the brackets are not here)
##{ x | x - 1 ≥ -\sqrt{5}} ## and ## { x | x - 1 ≥ \sqrt{5}}##
##{x | x ≥ 1 -\sqrt{5} }## and ## { x | x ≥ \sqrt{5} + 1}##...
Starting from the Heisenberg equation of motion, we have
$$ih \frac{\partial p}{\partial t} = [p, H]$$
which simplifies to $$ih \frac{\partial p}{\partial t} = -ih\frac{\partial V}{\partial x}$$
but this just results in ## \frac{\partial p}{\partial t} = -ih\frac{\partial V}{\partial x}## and...
Hi, PF, there goes the definition of General Riemann Sum, and later the exercise. Finally one doubt and my attempt:
(i) General Riemann Sums
Let ##P=\{x_0,x_1,x_2,\cdots,x_n\}##, where ##a=x_0<x_1<x_2<\cdots<x_n=b##, be a partition of ##[a,b]##, having norm ##||P||=\mbox{max}_{1<i<n}\Delta...
Hi,
I had to calculate the entropy in a task of a lattice gas and derive a formula for the pressure from it and got the following
$$P=\frac{k_b T}{a_0}\Bigl[ \ln(\frac{L}{a_0}-N(n-1)-\ln(\frac{L}{a_0}-nN) \Bigr]$$
But now I am supposed to calculate the following limit
$$\lim\limits_{a_0...
Let ##c## be a complex number with ##|c| \neq 1##. Find $$\lim_{n\to \infty} \frac{1}{n}\sum_{\ell = 1}^n \frac{\sin(e^{2\pi i \ell/n})}{1-ce^{-2\pi i \ell/n}}$$
In Section 3.4 of Shapiro & Teukolsky (1983), a simple derivation, due to Landau, of the maximum mass limit for white dwarfs and neutron stars is given. I will briefly describe it here and then pose my question.
The basic method is to derive an expression for the total energy (excluding rest...
I am confused by this question. If I try applying the theorem under Relevant Equations then it seems to me that the theorem cannot be applied since the limit of the denominator is zero. This question needs to be done without using derivatives since it appears in the Limits chapter, which...
This is probably a dumb question. I'm not a physicist and took basic physics a very long time ago.
If an object was in deep space, a long way away from gravitational fields and was subjected to a constant 1g acceleration in a straight line what prevents it from eventually exceeding light speed...
If we have two functions ##f(x)## such that ##\lim_{x \to \infty}f(x)=0## and ##g(x)=\sin x## for which ##\lim_{x \to \infty}g(x)## does not exist. Can you send me the Theorem and book where it is clearly written that
\lim_{x \to \infty}f(x)g(x)=0
I found that only for sequences, but it should...
I'm trying to compute ##\int_0^1 x^m \ln x \, \mathrm{d}x##. I'm wondering if the bit about the application of L'Hopital's rule was ok. Can anyone check?
Letting ##u = \ln x## and ##\mathrm{d}v = x^m##, we have ##\mathrm{d}u = \frac{1}{x}\mathrm{d}x ## and ##v = \frac{x^{m+1}}{m+1}##...
Right now, I am trying to prove this :
I tried to use this identity to solve it:
Then, the limit will become ##\frac {x}{e-e}##
However, the result is still ##\frac 0 0 ##
Could you please give me hints to solve this problem?
\lim_{x \rightarrow 1} \frac{x^2 - 1}{x-1}
For this, we first divide the numerator and denominator by (x-1) and we get
\lim_{x \rightarrow 1} (x+1)
Apparently, we can divide by (x-1) because x \neq 1, but then we plug in x = 1 and get 2 as the limit. Is x = 1 or x \neq 1? What exactly is...
I'm reading《Introducing Einstein's Relativity_ A Deeper Understanding Ed 2》on page 180,it says:
since we are interested in the Newtonian limit,we restrict our attention to the spatial part of the geodesic equation,i.e.when a=##\alpha####\quad ##,and we obtain,by using...
Hello everyone,
Our topology professor have introduced the standard topology of ##\mathbb{R}## as:
$$\tau=\left\{u\subset\mathbb{R}:\forall x\in u\exists\delta>0\ s.t.\ \left(x-\delta,x+\delta\right)\subset u\right\},$$
and the lower limit topology as...
Indeterminate forms are: ##\frac{0}{0}, \frac{\infty}{\infty} , \infty - \infty, 0 . \infty , 1^{\infty}, 0^{0}, \infty^{0}##
My answer:
4, 9, 15, 17, 20 are inderterminate forms
1. always has a fixed finite value, which is zero
2. ##0^{-\infty}=\frac{1}{0^{\infty}}=\frac{1}{0}=\infty## so it...
##i^\frac{1}{n}## has n roots. If one is not careful, the limit as ##n \to \infty## is 1. Simple proof: ##i=e^\frac{\pi i}{2}## or ##i^\frac{1}{n}=e^\frac{\pi i}{2n} \to e^0=1##.
This does not take into account the n roots, since ##i=e^{(\pi i)(2k+\frac{1}{2})}##.. Here ##\frac{k}{n} ## can...
I imagine ##f(x)## has horizontal asymptote at ##x=k##. Since the graph of ##f(x)## will be close to horizontal as ##x \rightarrow \infty##, the slope of the graph will be close to zero so ##\lim_{x \rightarrow \infty} f'(x) = \lim_{x \rightarrow \infty} f^{"} (x) = 0##
But how to put it in...
##f'(x_0)## is defined as:
$$f'(x_0)=\lim_{h \rightarrow 0} \frac{f(x_0+h)-f(x_0)}{h}$$
or
$$f'(x_0)=\lim_{x \rightarrow x_0} \frac{f(x)-f(x_0)}{x-x_0}$$
I can imagine that as ##n \rightarrow \infty## the value of ##f(b_n)## and ##f(a_n)## will approach ##f(x_0)## so the value of the limit will...
I know $$\lim_{h\rightarrow 0} af(h)+bf(2h)−f(0)=0$$
$$a+b=1$$
But I don't know how to find the second equation involving a and b. I imagine I need to somehow obtain ##h## in numerator so I can cross out with ##h## in denominator but I don't have idea how to get ##h## in the numerator.
Thanks
Summary: Definition: If M is a set and p is a point, then p is a limit point of M if every open interval containing p contains a point of M different from p.
Prove: that if H and K are sets and p is a limit point of H ∪ K,then p is a limit point of H or p is a limit point of K
In this proof I...
I have a probability distribution of the following form:
$$\displaystyle f \left(t \right) \, = \, \frac{\lambda ~e^{-\frac{\lambda ~t }{k }}}{k }, \, 0 < t, \, 0< \lambda, \, k = 1, 2, 3, \dots$$
It seems that this distribution is a limiting case of another distribution. The question is what...
The original differential equation is:
My solution is below, where C and D are constants. I have verified that it satisfies the original DE.
When I apply the first boundary condition, I obtain that , but I'm unsure where to go from there to apply the second boundary condition. I know that I...
Let's say we're given a sequence ##(s_n)## such that ##\lim s_n = s##. We have to prove that all subsequences of it converges to the same limit ##s##. Here is the standard proof:
Given ##\epsilon \gt 0## there exists an ##N## such that
$$
k \gt N \implies |s_k - s| \lt \varepsilon$$
Consider...
Was curious at the upper limit for neutron stars,
found this article stating one was found at around 700 / s
https://www.newscientist.com/article/dn8576-fast-spinning-neutron-star-smashes-speed-limit/
did not see the size, the article is behind a paywall, but it would have taken a radius of...