A difficulty in understanding the n-dimensional second order derivative. The Next CEO of Stack OverflowA difficulty in understanding the proof of completeness of $l_2$.Difficulty (2) in understanding thm4.2 in Israel Gohberg.A difficulty in understanding Theorem 4.3 in Israel Gohberg.A difficulty in understanding the Gram determinant.A difficulty in understanding a part of a solution of 4.4.4 PetovicA difficulty in understanding a proof for L'Hospital's rule (in Petrovic)A difficulty in understanding a step in a solution.A difficulty in understanding a statement in example 10.6.6 Petrovic.A difficulty in understanding theorem 10.6.7 in Petrovic.(n-dimensional intermediate value theorem)A difficulty in understanding the definition of “Spaces of Matrix Elements.”

How do I get the green key off the shelf in the Dobby level of Lego Harry Potter 2?

Horror movie/show or scene where a horse creature opens its mouth really wide and devours a man in a stables

How to Reset Passwords on Multiple Websites Easily?

How to make a variable always equal to the result of some calculations?

Need some help with wall behind rangetop

How can I quit an app using Terminal?

Rotate a column

Why doesn't a table tennis ball float on the surface? How do we calculate buoyancy here?

Can a single photon have an energy density?

WOW air has ceased operation, can I get my tickets refunded?

How to be diplomatic in refusing to write code that breaches the privacy of our users

What happens if you roll doubles 3 times then land on "Go to jail?"

Term for the "extreme-extension" version of a straw man fallacy?

How did people program for Consoles with multiple CPUs?

Visit to the USA with ESTA approved before trip to Iran

Can the Reverse Gravity spell affect the Meteor Swarm spell?

How do spells that require an ability check vs. the caster's spell save DC work?

How to make a software documentation "officially" citable?

Robert Sheckley short story about vacation spots being overwhelmed

Was a professor correct to chastise me for writing "Prof. X" rather than "Professor X"?

How do I construct this japanese bowl?

How to safely derail a train during transit?

Why didn't Theresa May consult with Parliament before negotiating a deal with the EU?

If I blow insulation everywhere in my attic except the door trap, will heat escape through it?



A difficulty in understanding the n-dimensional second order derivative.



The Next CEO of Stack OverflowA difficulty in understanding the proof of completeness of $l_2$.Difficulty (2) in understanding thm4.2 in Israel Gohberg.A difficulty in understanding Theorem 4.3 in Israel Gohberg.A difficulty in understanding the Gram determinant.A difficulty in understanding a part of a solution of 4.4.4 PetovicA difficulty in understanding a proof for L'Hospital's rule (in Petrovic)A difficulty in understanding a step in a solution.A difficulty in understanding a statement in example 10.6.6 Petrovic.A difficulty in understanding theorem 10.6.7 in Petrovic.(n-dimensional intermediate value theorem)A difficulty in understanding the definition of “Spaces of Matrix Elements.”










0












$begingroup$


The example and its solution is given below:




enter image description here



enter image description here




But I do not understand why in the calculation of $D^2 f(2,3)(u)^2$ the $u^2$ takes this form ....$ u_1^2 + u_1u_2 + u_2^2$ from where the term $u_1u_2$ comes?...... could anyone explain this for me please?



Edit:
I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement..... but I do not understand this statement.










share|cite|improve this question











$endgroup$







  • 1




    $begingroup$
    What is this from??
    $endgroup$
    – Randall
    Mar 18 at 12:49










  • $begingroup$
    $ u_1^2 + u_1u_2 + u_2^2$ @Randall from where the term $u_1u_2$ comes?
    $endgroup$
    – hopefully
    Mar 18 at 12:51










  • $begingroup$
    No, the book/notes.
    $endgroup$
    – Randall
    Mar 18 at 12:52










  • $begingroup$
    Petrovic "Advanced calculus theory and practice" @Randall
    $endgroup$
    – hopefully
    Mar 18 at 12:54










  • $begingroup$
    I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement.@Randall
    $endgroup$
    – hopefully
    Mar 18 at 13:01















0












$begingroup$


The example and its solution is given below:




enter image description here



enter image description here




But I do not understand why in the calculation of $D^2 f(2,3)(u)^2$ the $u^2$ takes this form ....$ u_1^2 + u_1u_2 + u_2^2$ from where the term $u_1u_2$ comes?...... could anyone explain this for me please?



Edit:
I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement..... but I do not understand this statement.










share|cite|improve this question











$endgroup$







  • 1




    $begingroup$
    What is this from??
    $endgroup$
    – Randall
    Mar 18 at 12:49










  • $begingroup$
    $ u_1^2 + u_1u_2 + u_2^2$ @Randall from where the term $u_1u_2$ comes?
    $endgroup$
    – hopefully
    Mar 18 at 12:51










  • $begingroup$
    No, the book/notes.
    $endgroup$
    – Randall
    Mar 18 at 12:52










  • $begingroup$
    Petrovic "Advanced calculus theory and practice" @Randall
    $endgroup$
    – hopefully
    Mar 18 at 12:54










  • $begingroup$
    I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement.@Randall
    $endgroup$
    – hopefully
    Mar 18 at 13:01













0












0








0





$begingroup$


The example and its solution is given below:




enter image description here



enter image description here




But I do not understand why in the calculation of $D^2 f(2,3)(u)^2$ the $u^2$ takes this form ....$ u_1^2 + u_1u_2 + u_2^2$ from where the term $u_1u_2$ comes?...... could anyone explain this for me please?



Edit:
I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement..... but I do not understand this statement.










share|cite|improve this question











$endgroup$




The example and its solution is given below:




enter image description here



enter image description here




But I do not understand why in the calculation of $D^2 f(2,3)(u)^2$ the $u^2$ takes this form ....$ u_1^2 + u_1u_2 + u_2^2$ from where the term $u_1u_2$ comes?...... could anyone explain this for me please?



Edit:
I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement..... but I do not understand this statement.







real-analysis calculus linear-algebra analysis multivariable-calculus






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Mar 18 at 13:02







hopefully

















asked Mar 18 at 12:48









hopefullyhopefully

277214




277214







  • 1




    $begingroup$
    What is this from??
    $endgroup$
    – Randall
    Mar 18 at 12:49










  • $begingroup$
    $ u_1^2 + u_1u_2 + u_2^2$ @Randall from where the term $u_1u_2$ comes?
    $endgroup$
    – hopefully
    Mar 18 at 12:51










  • $begingroup$
    No, the book/notes.
    $endgroup$
    – Randall
    Mar 18 at 12:52










  • $begingroup$
    Petrovic "Advanced calculus theory and practice" @Randall
    $endgroup$
    – hopefully
    Mar 18 at 12:54










  • $begingroup$
    I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement.@Randall
    $endgroup$
    – hopefully
    Mar 18 at 13:01












  • 1




    $begingroup$
    What is this from??
    $endgroup$
    – Randall
    Mar 18 at 12:49










  • $begingroup$
    $ u_1^2 + u_1u_2 + u_2^2$ @Randall from where the term $u_1u_2$ comes?
    $endgroup$
    – hopefully
    Mar 18 at 12:51










  • $begingroup$
    No, the book/notes.
    $endgroup$
    – Randall
    Mar 18 at 12:52










  • $begingroup$
    Petrovic "Advanced calculus theory and practice" @Randall
    $endgroup$
    – hopefully
    Mar 18 at 12:54










  • $begingroup$
    I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement.@Randall
    $endgroup$
    – hopefully
    Mar 18 at 13:01







1




1




$begingroup$
What is this from??
$endgroup$
– Randall
Mar 18 at 12:49




$begingroup$
What is this from??
$endgroup$
– Randall
Mar 18 at 12:49












$begingroup$
$ u_1^2 + u_1u_2 + u_2^2$ @Randall from where the term $u_1u_2$ comes?
$endgroup$
– hopefully
Mar 18 at 12:51




$begingroup$
$ u_1^2 + u_1u_2 + u_2^2$ @Randall from where the term $u_1u_2$ comes?
$endgroup$
– hopefully
Mar 18 at 12:51












$begingroup$
No, the book/notes.
$endgroup$
– Randall
Mar 18 at 12:52




$begingroup$
No, the book/notes.
$endgroup$
– Randall
Mar 18 at 12:52












$begingroup$
Petrovic "Advanced calculus theory and practice" @Randall
$endgroup$
– hopefully
Mar 18 at 12:54




$begingroup$
Petrovic "Advanced calculus theory and practice" @Randall
$endgroup$
– hopefully
Mar 18 at 12:54












$begingroup$
I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement.@Randall
$endgroup$
– hopefully
Mar 18 at 13:01




$begingroup$
I remember that my professor said that the dot product in two dimensional is just the square of the term but I do not understand this statement.@Randall
$endgroup$
– hopefully
Mar 18 at 13:01










1 Answer
1






active

oldest

votes


















1












$begingroup$

The object $q:=D^2f(2,3)$ is a quadratic form in the increment variable $bf u=(u_1,u_2)$. The vector $bf u$ is attached at the point $bf p=(2,3)inrm dom(f)$, in other words: $bf u$ is a vector in the tangent space $T_bf p$. One has
$$q(bf u)=sum_i, >k=1^2 f_.ik(bf p)>u_iu_k=[u_1 u_2]left[matrix-6&6cr 6&30crright]left[matrixu_1cr u_2crright]=-6u_1^2+12u_1u_2+30 u_2^2 .$$






share|cite|improve this answer











$endgroup$












  • $begingroup$
    what is $T_p$?
    $endgroup$
    – hopefully
    Mar 18 at 13:12











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
);



);













draft saved

draft discarded


















StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3152741%2fa-difficulty-in-understanding-the-n-dimensional-second-order-derivative%23new-answer', 'question_page');

);

Post as a guest















Required, but never shown

























1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

The object $q:=D^2f(2,3)$ is a quadratic form in the increment variable $bf u=(u_1,u_2)$. The vector $bf u$ is attached at the point $bf p=(2,3)inrm dom(f)$, in other words: $bf u$ is a vector in the tangent space $T_bf p$. One has
$$q(bf u)=sum_i, >k=1^2 f_.ik(bf p)>u_iu_k=[u_1 u_2]left[matrix-6&6cr 6&30crright]left[matrixu_1cr u_2crright]=-6u_1^2+12u_1u_2+30 u_2^2 .$$






share|cite|improve this answer











$endgroup$












  • $begingroup$
    what is $T_p$?
    $endgroup$
    – hopefully
    Mar 18 at 13:12















1












$begingroup$

The object $q:=D^2f(2,3)$ is a quadratic form in the increment variable $bf u=(u_1,u_2)$. The vector $bf u$ is attached at the point $bf p=(2,3)inrm dom(f)$, in other words: $bf u$ is a vector in the tangent space $T_bf p$. One has
$$q(bf u)=sum_i, >k=1^2 f_.ik(bf p)>u_iu_k=[u_1 u_2]left[matrix-6&6cr 6&30crright]left[matrixu_1cr u_2crright]=-6u_1^2+12u_1u_2+30 u_2^2 .$$






share|cite|improve this answer











$endgroup$












  • $begingroup$
    what is $T_p$?
    $endgroup$
    – hopefully
    Mar 18 at 13:12













1












1








1





$begingroup$

The object $q:=D^2f(2,3)$ is a quadratic form in the increment variable $bf u=(u_1,u_2)$. The vector $bf u$ is attached at the point $bf p=(2,3)inrm dom(f)$, in other words: $bf u$ is a vector in the tangent space $T_bf p$. One has
$$q(bf u)=sum_i, >k=1^2 f_.ik(bf p)>u_iu_k=[u_1 u_2]left[matrix-6&6cr 6&30crright]left[matrixu_1cr u_2crright]=-6u_1^2+12u_1u_2+30 u_2^2 .$$






share|cite|improve this answer











$endgroup$



The object $q:=D^2f(2,3)$ is a quadratic form in the increment variable $bf u=(u_1,u_2)$. The vector $bf u$ is attached at the point $bf p=(2,3)inrm dom(f)$, in other words: $bf u$ is a vector in the tangent space $T_bf p$. One has
$$q(bf u)=sum_i, >k=1^2 f_.ik(bf p)>u_iu_k=[u_1 u_2]left[matrix-6&6cr 6&30crright]left[matrixu_1cr u_2crright]=-6u_1^2+12u_1u_2+30 u_2^2 .$$







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Mar 18 at 13:41

























answered Mar 18 at 13:10









Christian BlatterChristian Blatter

175k8115327




175k8115327











  • $begingroup$
    what is $T_p$?
    $endgroup$
    – hopefully
    Mar 18 at 13:12
















  • $begingroup$
    what is $T_p$?
    $endgroup$
    – hopefully
    Mar 18 at 13:12















$begingroup$
what is $T_p$?
$endgroup$
– hopefully
Mar 18 at 13:12




$begingroup$
what is $T_p$?
$endgroup$
– hopefully
Mar 18 at 13:12

















draft saved

draft discarded
















































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.




draft saved


draft discarded














StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3152741%2fa-difficulty-in-understanding-the-n-dimensional-second-order-derivative%23new-answer', 'question_page');

);

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







Popular posts from this blog

Lowndes Grove History Architecture References Navigation menu32°48′6″N 79°57′58″W / 32.80167°N 79.96611°W / 32.80167; -79.9661132°48′6″N 79°57′58″W / 32.80167°N 79.96611°W / 32.80167; -79.9661178002500"National Register Information System"Historic houses of South Carolina"Lowndes Grove""+32° 48' 6.00", −79° 57' 58.00""Lowndes Grove, Charleston County (260 St. Margaret St., Charleston)""Lowndes Grove"The Charleston ExpositionIt Happened in South Carolina"Lowndes Grove (House), Saint Margaret Street & Sixth Avenue, Charleston, Charleston County, SC(Photographs)"Plantations of the Carolina Low Countrye

random experiment with two different functions on unit interval Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 23, 2019 at 00:00UTC (8:00pm US/Eastern)Random variable and probability space notionsRandom Walk with EdgesFinding functions where the increase over a random interval is Poisson distributedNumber of days until dayCan an observed event in fact be of zero probability?Unit random processmodels of coins and uniform distributionHow to get the number of successes given $n$ trials , probability $P$ and a random variable $X$Absorbing Markov chain in a computer. Is “almost every” turned into always convergence in computer executions?Stopped random walk is not uniformly integrable

How should I support this large drywall patch? Planned maintenance scheduled April 23, 2019 at 00:00UTC (8:00pm US/Eastern) Announcing the arrival of Valued Associate #679: Cesar Manara Unicorn Meta Zoo #1: Why another podcast?How do I cover large gaps in drywall?How do I keep drywall around a patch from crumbling?Can I glue a second layer of drywall?How to patch long strip on drywall?Large drywall patch: how to avoid bulging seams?Drywall Mesh Patch vs. Bulge? To remove or not to remove?How to fix this drywall job?Prep drywall before backsplashWhat's the best way to fix this horrible drywall patch job?Drywall patching using 3M Patch Plus Primer