Determine the value, when defined The Next CEO of Stack OverflowHow can calculate this limit?Finding the value of one-sided limits and greatest integer function.Find the limit $lim_ nrightarrow infty fracleftlfloorfrac3n10rightrfloorn$What is the value of $lim _xto 0leftlfloorfractan x sin xx^2rightrfloor$Finding a delta for the greatest integer function given an epsilon = 1/2If $lfloorcdotrfloor$ denotes the greatest integer function $ninmathbb N$, what is $lim_xto 0leftlfloorfracnsin(x) x rightrfloor$?Find the value of $lim_xto 0 fracsinxx$Can Greatest integer function and limit be InterchangedEvaluate $ lim_x to -0.5^- leftlfloorfrac1x leftlfloor frac-1x rightrfloorrightrfloor$Let $x>0$ , $lfloor xrfloor$ denotes the greatest integer less than or equal to $x$. Then find limit
Can you replace a racial trait cantrip when leveling up?
Why is the US ranked as #45 in Press Freedom ratings, despite its extremely permissive free speech laws?
What happens if you roll doubles 3 times then land on "Go to jail?"
Why has the US not been more assertive in confronting Russia in recent years?
How to safely derail a train during transit?
What happened in Rome, when the western empire "fell"?
MessageLevel in QGIS3
Real integral using residue theorem - why doesn't this work?
Make solar eclipses exceedingly rare, but still have new moons
Complex fractions
How did the Bene Gesserit know how to make a Kwisatz Haderach?
Inappropriate reference requests from Journal reviewers
Are there any limitations on attacking while grappling?
Unreliable Magic - Is it worth it?
How does the Z80 determine which peripheral sent an interrupt?
What flight has the highest ratio of time difference to flight time?
What benefits would be gained by using human laborers instead of drones in deep sea mining?
What is the result of assigning to std::vector<T>::begin()?
Written every which way
What was the first Unix version to run on a microcomputer?
Is "for causing autism in X" grammatical?
How do we know the LHC results are robust?
Multiple labels for a single equation
Why do professional authors make "consistency" mistakes? And how to avoid them?
Determine the value, when defined
The Next CEO of Stack OverflowHow can calculate this limit?Finding the value of one-sided limits and greatest integer function.Find the limit $lim_ nrightarrow infty fracleftlfloorfrac3n10rightrfloorn$What is the value of $lim _xto 0leftlfloorfractan x sin xx^2rightrfloor$Finding a delta for the greatest integer function given an epsilon = 1/2If $lfloorcdotrfloor$ denotes the greatest integer function $ninmathbb N$, what is $lim_xto 0leftlfloorfracnsin(x) x rightrfloor$?Find the value of $lim_xto 0 fracsinxx$Can Greatest integer function and limit be InterchangedEvaluate $ lim_x to -0.5^- leftlfloorfrac1x leftlfloor frac-1x rightrfloorrightrfloor$Let $x>0$ , $lfloor xrfloor$ denotes the greatest integer less than or equal to $x$. Then find limit
$begingroup$
Determine the value, when defined, of $$lim_xtoinfty frac1x^2-lfloor xrfloor$$ where $lfloor xrfloor$ is the greatest integer.
I know $lim_xtoinfty lfloor xrfloor = infty$ and $lim_xtoinfty x^2$=$infty$ but how do I combine them in order to get $$lim_xtoinfty frac1x^2-[x]$$
limits analysis
$endgroup$
add a comment |
$begingroup$
Determine the value, when defined, of $$lim_xtoinfty frac1x^2-lfloor xrfloor$$ where $lfloor xrfloor$ is the greatest integer.
I know $lim_xtoinfty lfloor xrfloor = infty$ and $lim_xtoinfty x^2$=$infty$ but how do I combine them in order to get $$lim_xtoinfty frac1x^2-[x]$$
limits analysis
$endgroup$
$begingroup$
What do you mean by $[x]$?
$endgroup$
– copper.hat
2 days ago
$begingroup$
$lim_xtoinfty lfloor xrfloor =infty,$ not $-infty.$
$endgroup$
– Thomas Andrews
2 days ago
$begingroup$
copper.hat greatest integer
$endgroup$
– user597188
2 days ago
add a comment |
$begingroup$
Determine the value, when defined, of $$lim_xtoinfty frac1x^2-lfloor xrfloor$$ where $lfloor xrfloor$ is the greatest integer.
I know $lim_xtoinfty lfloor xrfloor = infty$ and $lim_xtoinfty x^2$=$infty$ but how do I combine them in order to get $$lim_xtoinfty frac1x^2-[x]$$
limits analysis
$endgroup$
Determine the value, when defined, of $$lim_xtoinfty frac1x^2-lfloor xrfloor$$ where $lfloor xrfloor$ is the greatest integer.
I know $lim_xtoinfty lfloor xrfloor = infty$ and $lim_xtoinfty x^2$=$infty$ but how do I combine them in order to get $$lim_xtoinfty frac1x^2-[x]$$
limits analysis
limits analysis
edited 2 days ago
user597188
asked 2 days ago
user597188user597188
235
235
$begingroup$
What do you mean by $[x]$?
$endgroup$
– copper.hat
2 days ago
$begingroup$
$lim_xtoinfty lfloor xrfloor =infty,$ not $-infty.$
$endgroup$
– Thomas Andrews
2 days ago
$begingroup$
copper.hat greatest integer
$endgroup$
– user597188
2 days ago
add a comment |
$begingroup$
What do you mean by $[x]$?
$endgroup$
– copper.hat
2 days ago
$begingroup$
$lim_xtoinfty lfloor xrfloor =infty,$ not $-infty.$
$endgroup$
– Thomas Andrews
2 days ago
$begingroup$
copper.hat greatest integer
$endgroup$
– user597188
2 days ago
$begingroup$
What do you mean by $[x]$?
$endgroup$
– copper.hat
2 days ago
$begingroup$
What do you mean by $[x]$?
$endgroup$
– copper.hat
2 days ago
$begingroup$
$lim_xtoinfty lfloor xrfloor =infty,$ not $-infty.$
$endgroup$
– Thomas Andrews
2 days ago
$begingroup$
$lim_xtoinfty lfloor xrfloor =infty,$ not $-infty.$
$endgroup$
– Thomas Andrews
2 days ago
$begingroup$
copper.hat greatest integer
$endgroup$
– user597188
2 days ago
$begingroup$
copper.hat greatest integer
$endgroup$
– user597188
2 days ago
add a comment |
3 Answers
3
active
oldest
votes
$begingroup$
Notice that $ x-1 leq [x]leq x$ so:
$$lim_xto inftyfrac1x^2-x+1leqlim_xto infty frac1x^2-[x]leq lim_xto infty frac1x^2-x$$
So:
$$0leqlim_xto infty frac1x^2-[x]leq 0$$
And:
$$lim_xto infty frac1x^2-[x]=0$$
:)
New contributor
$endgroup$
add a comment |
$begingroup$
We always have $lfloor xrfloorle x$.
For $x ge 2$ we have $x^2 over 2 ge x$.
Hence, if $x ge 2$, we have $x^2-lfloor xrfloor ge x^2 -x ge x^2 over 2$ and
so
$1 over x^2-lfloor xrfloor le 2 over x^2$.
$endgroup$
add a comment |
$begingroup$
Is in not obvious that $x^2$ grows proportionally faster than $[x]$ so $x^2 - [x]to infty$?
To verify:
$x ge [x] > 0$ so $x^2 ge [x]^2$ and $frac 1 x^2 - [x] le frac 1[x]^2 - [x] = frac 1[x]([x] - 1)< frac 1([x]-1)^2to 0$.
To formalize:
If $epsilon > 0$ and we want $[x]- 1 > sqrtfrac 1epsilon$, which we can get if we choose $x > lceil sqrtfrac 1epsilon rceil + 1=N$.
Now if $x > N =lceil sqrtfrac 1epsilon rceil + 1$ then $[x] ge lceil sqrtfrac 1epsilon rceil + 1 ge sqrtfrac 1epsilon + 1$
$[x]- 1 ge sqrtfrac 1 epsilon$
$x^2 - [x]>[x]^2 - [x]=[x]([x]- 1)>([x]-1)^2 ge frac 1epsilon$
$frac 1x^2 -[x] < epsilon$.
So $limlimits_xto infty frac 1x^2 -[x] = infty$.
$endgroup$
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("mathjaxEditing", function ()
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
);
);
, "mathjax-editing");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "69"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3164688%2fdetermine-the-value-when-defined%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Notice that $ x-1 leq [x]leq x$ so:
$$lim_xto inftyfrac1x^2-x+1leqlim_xto infty frac1x^2-[x]leq lim_xto infty frac1x^2-x$$
So:
$$0leqlim_xto infty frac1x^2-[x]leq 0$$
And:
$$lim_xto infty frac1x^2-[x]=0$$
:)
New contributor
$endgroup$
add a comment |
$begingroup$
Notice that $ x-1 leq [x]leq x$ so:
$$lim_xto inftyfrac1x^2-x+1leqlim_xto infty frac1x^2-[x]leq lim_xto infty frac1x^2-x$$
So:
$$0leqlim_xto infty frac1x^2-[x]leq 0$$
And:
$$lim_xto infty frac1x^2-[x]=0$$
:)
New contributor
$endgroup$
add a comment |
$begingroup$
Notice that $ x-1 leq [x]leq x$ so:
$$lim_xto inftyfrac1x^2-x+1leqlim_xto infty frac1x^2-[x]leq lim_xto infty frac1x^2-x$$
So:
$$0leqlim_xto infty frac1x^2-[x]leq 0$$
And:
$$lim_xto infty frac1x^2-[x]=0$$
:)
New contributor
$endgroup$
Notice that $ x-1 leq [x]leq x$ so:
$$lim_xto inftyfrac1x^2-x+1leqlim_xto infty frac1x^2-[x]leq lim_xto infty frac1x^2-x$$
So:
$$0leqlim_xto infty frac1x^2-[x]leq 0$$
And:
$$lim_xto infty frac1x^2-[x]=0$$
:)
New contributor
New contributor
answered 2 days ago
EurekaEureka
423112
423112
New contributor
New contributor
add a comment |
add a comment |
$begingroup$
We always have $lfloor xrfloorle x$.
For $x ge 2$ we have $x^2 over 2 ge x$.
Hence, if $x ge 2$, we have $x^2-lfloor xrfloor ge x^2 -x ge x^2 over 2$ and
so
$1 over x^2-lfloor xrfloor le 2 over x^2$.
$endgroup$
add a comment |
$begingroup$
We always have $lfloor xrfloorle x$.
For $x ge 2$ we have $x^2 over 2 ge x$.
Hence, if $x ge 2$, we have $x^2-lfloor xrfloor ge x^2 -x ge x^2 over 2$ and
so
$1 over x^2-lfloor xrfloor le 2 over x^2$.
$endgroup$
add a comment |
$begingroup$
We always have $lfloor xrfloorle x$.
For $x ge 2$ we have $x^2 over 2 ge x$.
Hence, if $x ge 2$, we have $x^2-lfloor xrfloor ge x^2 -x ge x^2 over 2$ and
so
$1 over x^2-lfloor xrfloor le 2 over x^2$.
$endgroup$
We always have $lfloor xrfloorle x$.
For $x ge 2$ we have $x^2 over 2 ge x$.
Hence, if $x ge 2$, we have $x^2-lfloor xrfloor ge x^2 -x ge x^2 over 2$ and
so
$1 over x^2-lfloor xrfloor le 2 over x^2$.
edited 2 days ago
answered 2 days ago
copper.hatcopper.hat
128k559161
128k559161
add a comment |
add a comment |
$begingroup$
Is in not obvious that $x^2$ grows proportionally faster than $[x]$ so $x^2 - [x]to infty$?
To verify:
$x ge [x] > 0$ so $x^2 ge [x]^2$ and $frac 1 x^2 - [x] le frac 1[x]^2 - [x] = frac 1[x]([x] - 1)< frac 1([x]-1)^2to 0$.
To formalize:
If $epsilon > 0$ and we want $[x]- 1 > sqrtfrac 1epsilon$, which we can get if we choose $x > lceil sqrtfrac 1epsilon rceil + 1=N$.
Now if $x > N =lceil sqrtfrac 1epsilon rceil + 1$ then $[x] ge lceil sqrtfrac 1epsilon rceil + 1 ge sqrtfrac 1epsilon + 1$
$[x]- 1 ge sqrtfrac 1 epsilon$
$x^2 - [x]>[x]^2 - [x]=[x]([x]- 1)>([x]-1)^2 ge frac 1epsilon$
$frac 1x^2 -[x] < epsilon$.
So $limlimits_xto infty frac 1x^2 -[x] = infty$.
$endgroup$
add a comment |
$begingroup$
Is in not obvious that $x^2$ grows proportionally faster than $[x]$ so $x^2 - [x]to infty$?
To verify:
$x ge [x] > 0$ so $x^2 ge [x]^2$ and $frac 1 x^2 - [x] le frac 1[x]^2 - [x] = frac 1[x]([x] - 1)< frac 1([x]-1)^2to 0$.
To formalize:
If $epsilon > 0$ and we want $[x]- 1 > sqrtfrac 1epsilon$, which we can get if we choose $x > lceil sqrtfrac 1epsilon rceil + 1=N$.
Now if $x > N =lceil sqrtfrac 1epsilon rceil + 1$ then $[x] ge lceil sqrtfrac 1epsilon rceil + 1 ge sqrtfrac 1epsilon + 1$
$[x]- 1 ge sqrtfrac 1 epsilon$
$x^2 - [x]>[x]^2 - [x]=[x]([x]- 1)>([x]-1)^2 ge frac 1epsilon$
$frac 1x^2 -[x] < epsilon$.
So $limlimits_xto infty frac 1x^2 -[x] = infty$.
$endgroup$
add a comment |
$begingroup$
Is in not obvious that $x^2$ grows proportionally faster than $[x]$ so $x^2 - [x]to infty$?
To verify:
$x ge [x] > 0$ so $x^2 ge [x]^2$ and $frac 1 x^2 - [x] le frac 1[x]^2 - [x] = frac 1[x]([x] - 1)< frac 1([x]-1)^2to 0$.
To formalize:
If $epsilon > 0$ and we want $[x]- 1 > sqrtfrac 1epsilon$, which we can get if we choose $x > lceil sqrtfrac 1epsilon rceil + 1=N$.
Now if $x > N =lceil sqrtfrac 1epsilon rceil + 1$ then $[x] ge lceil sqrtfrac 1epsilon rceil + 1 ge sqrtfrac 1epsilon + 1$
$[x]- 1 ge sqrtfrac 1 epsilon$
$x^2 - [x]>[x]^2 - [x]=[x]([x]- 1)>([x]-1)^2 ge frac 1epsilon$
$frac 1x^2 -[x] < epsilon$.
So $limlimits_xto infty frac 1x^2 -[x] = infty$.
$endgroup$
Is in not obvious that $x^2$ grows proportionally faster than $[x]$ so $x^2 - [x]to infty$?
To verify:
$x ge [x] > 0$ so $x^2 ge [x]^2$ and $frac 1 x^2 - [x] le frac 1[x]^2 - [x] = frac 1[x]([x] - 1)< frac 1([x]-1)^2to 0$.
To formalize:
If $epsilon > 0$ and we want $[x]- 1 > sqrtfrac 1epsilon$, which we can get if we choose $x > lceil sqrtfrac 1epsilon rceil + 1=N$.
Now if $x > N =lceil sqrtfrac 1epsilon rceil + 1$ then $[x] ge lceil sqrtfrac 1epsilon rceil + 1 ge sqrtfrac 1epsilon + 1$
$[x]- 1 ge sqrtfrac 1 epsilon$
$x^2 - [x]>[x]^2 - [x]=[x]([x]- 1)>([x]-1)^2 ge frac 1epsilon$
$frac 1x^2 -[x] < epsilon$.
So $limlimits_xto infty frac 1x^2 -[x] = infty$.
answered 2 days ago
fleabloodfleablood
73.6k22891
73.6k22891
add a comment |
add a comment |
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3164688%2fdetermine-the-value-when-defined%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
$begingroup$
What do you mean by $[x]$?
$endgroup$
– copper.hat
2 days ago
$begingroup$
$lim_xtoinfty lfloor xrfloor =infty,$ not $-infty.$
$endgroup$
– Thomas Andrews
2 days ago
$begingroup$
copper.hat greatest integer
$endgroup$
– user597188
2 days ago