Form of series solution in Differential equation

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
0
down vote

favorite












Find the equation that doesn't have a series solution in form of
$$y(x)=sum_n=0^inftya_nx^n $$



$$ 1.;;fracd^2ydx^2+fracsin xxy=0 qquad 2.;;fracd^2ydx^2+fraccos xxy=0$$ $$ 3.;;fracd^2ydx^2+sin(x)y=0qquad 4.;;fracd^2ydx^2+cos(x)y=0$$



$y''+P(x)y'+Q(x)y=0 $



It seems $Q(x)$ in every choice is analytic to me. How should I solve it?




differential-equations




share|cite|improve this question

















  • 3




    whats the limit $cos(x)/x$ as $xto 0$?
    – Calvin Khor
    Jul 27 at 12:28










  • In one of these choices, $Q(x)$ is not analytic at $x=0$
    – Dylan
    Jul 27 at 12:45










  • Isn't cosx/x representable as power series which means analytic?
    – NK Yu
    Jul 27 at 12:52






  • 1




    Try to find the power series of $cos x/x$. You'll see that the leading term is $1/x$
    – Dylan
    Jul 27 at 12:53







  • 1




    @NKYu Do the same calculation for $frac sin x x$ and see the difference.
    – Isham
    Jul 27 at 13:03














up vote
0
down vote

favorite












Find the equation that doesn't have a series solution in form of
$$y(x)=sum_n=0^inftya_nx^n $$



$$ 1.;;fracd^2ydx^2+fracsin xxy=0 qquad 2.;;fracd^2ydx^2+fraccos xxy=0$$ $$ 3.;;fracd^2ydx^2+sin(x)y=0qquad 4.;;fracd^2ydx^2+cos(x)y=0$$



$y''+P(x)y'+Q(x)y=0 $



It seems $Q(x)$ in every choice is analytic to me. How should I solve it?




differential-equations




share|cite|improve this question

















  • 3




    whats the limit $cos(x)/x$ as $xto 0$?
    – Calvin Khor
    Jul 27 at 12:28










  • In one of these choices, $Q(x)$ is not analytic at $x=0$
    – Dylan
    Jul 27 at 12:45










  • Isn't cosx/x representable as power series which means analytic?
    – NK Yu
    Jul 27 at 12:52






  • 1




    Try to find the power series of $cos x/x$. You'll see that the leading term is $1/x$
    – Dylan
    Jul 27 at 12:53







  • 1




    @NKYu Do the same calculation for $frac sin x x$ and see the difference.
    – Isham
    Jul 27 at 13:03












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Find the equation that doesn't have a series solution in form of
$$y(x)=sum_n=0^inftya_nx^n $$



$$ 1.;;fracd^2ydx^2+fracsin xxy=0 qquad 2.;;fracd^2ydx^2+fraccos xxy=0$$ $$ 3.;;fracd^2ydx^2+sin(x)y=0qquad 4.;;fracd^2ydx^2+cos(x)y=0$$



$y''+P(x)y'+Q(x)y=0 $



It seems $Q(x)$ in every choice is analytic to me. How should I solve it?




differential-equations




share|cite|improve this question













Find the equation that doesn't have a series solution in form of
$$y(x)=sum_n=0^inftya_nx^n $$



$$ 1.;;fracd^2ydx^2+fracsin xxy=0 qquad 2.;;fracd^2ydx^2+fraccos xxy=0$$ $$ 3.;;fracd^2ydx^2+sin(x)y=0qquad 4.;;fracd^2ydx^2+cos(x)y=0$$



$y''+P(x)y'+Q(x)y=0 $



It seems $Q(x)$ in every choice is analytic to me. How should I solve it?





differential-equations





share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Jul 27 at 12:26









Bernard

110k635102




110k635102









asked Jul 27 at 12:19









NK Yu

1847




1847







  • 3




    whats the limit $cos(x)/x$ as $xto 0$?
    – Calvin Khor
    Jul 27 at 12:28










  • In one of these choices, $Q(x)$ is not analytic at $x=0$
    – Dylan
    Jul 27 at 12:45










  • Isn't cosx/x representable as power series which means analytic?
    – NK Yu
    Jul 27 at 12:52






  • 1




    Try to find the power series of $cos x/x$. You'll see that the leading term is $1/x$
    – Dylan
    Jul 27 at 12:53







  • 1




    @NKYu Do the same calculation for $frac sin x x$ and see the difference.
    – Isham
    Jul 27 at 13:03












  • 3




    whats the limit $cos(x)/x$ as $xto 0$?
    – Calvin Khor
    Jul 27 at 12:28










  • In one of these choices, $Q(x)$ is not analytic at $x=0$
    – Dylan
    Jul 27 at 12:45










  • Isn't cosx/x representable as power series which means analytic?
    – NK Yu
    Jul 27 at 12:52






  • 1




    Try to find the power series of $cos x/x$. You'll see that the leading term is $1/x$
    – Dylan
    Jul 27 at 12:53







  • 1




    @NKYu Do the same calculation for $frac sin x x$ and see the difference.
    – Isham
    Jul 27 at 13:03







3




3




whats the limit $cos(x)/x$ as $xto 0$?
– Calvin Khor
Jul 27 at 12:28




whats the limit $cos(x)/x$ as $xto 0$?
– Calvin Khor
Jul 27 at 12:28












In one of these choices, $Q(x)$ is not analytic at $x=0$
– Dylan
Jul 27 at 12:45




In one of these choices, $Q(x)$ is not analytic at $x=0$
– Dylan
Jul 27 at 12:45












Isn't cosx/x representable as power series which means analytic?
– NK Yu
Jul 27 at 12:52




Isn't cosx/x representable as power series which means analytic?
– NK Yu
Jul 27 at 12:52




1




1




Try to find the power series of $cos x/x$. You'll see that the leading term is $1/x$
– Dylan
Jul 27 at 12:53





Try to find the power series of $cos x/x$. You'll see that the leading term is $1/x$
– Dylan
Jul 27 at 12:53





1




1




@NKYu Do the same calculation for $frac sin x x$ and see the difference.
– Isham
Jul 27 at 13:03




@NKYu Do the same calculation for $frac sin x x$ and see the difference.
– Isham
Jul 27 at 13:03















active

oldest

votes











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',
convertImagesToLinks: true,
noModals: false,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
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%2f2864360%2fform-of-series-solution-in-differential-equation%23new-answer', 'question_page');

);

Post as a guest






















active

oldest

votes













active

oldest

votes









active

oldest

votes






active

oldest

votes










 

draft saved


draft discarded


























 


draft saved


draft discarded














StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2864360%2fform-of-series-solution-in-differential-equation%23new-answer', 'question_page');

);

Post as a guest
































































Comments

Post a Comment

Popular posts from this blog

What is the equation of a 3D cone with generalised tilt?

Image
Clash Royale CLAN TAG #URR8PPP up vote 2 down vote favorite What is the equation of a 3D cone with generalized tilt? I've noticed that in most equations given to represent a cone, there is no parameter which defines the tilt of the cone in 3D space and that most of them have their point at the origin $(0,0,0)$ - I was wondering if anyone could give me a more generalized cone equation for a cone in any position in 3D space 3d share | cite | improve this question edited Jul 25 '16 at 0:05 ervx 9,425 3 13 36 asked Jul 24 '16 at 15:38 Charlene 11 2 2 Welcome to Math.SE! Could you please explain a few things to help people give an answer useful to you: 1. What do you mean by "generalized tilt"? 2. Are you asking about a right circular cone? Does the angle at the vertex matter? 3. What form of answer (implicit, parametric...?) are you looking for? 4. If this is homework, what tools do you have available, an...
Read more

Color the edges and diagonals of a regular polygon

Image
Clash Royale CLAN TAG #URR8PPP up vote 5 down vote favorite 1 Here is the problem: For what $n$ is it possible to color the edges and diagonals of an $n$-side regular polygon with $dfracbinomn23$ colors, such that you use every color exactly three times and for every color the three segments (edges or diagonals) with that color form a triangle? Trivially $nequiv 0 text or 1 pmod3$. I can also prove that if the statement is true for $k$ than it is true for $3k$ as well. How to finish? Please help! Thanks combinatorial-geometry share | cite | improve this question edited Aug 6 at 21:57 alcana 118 4 asked Aug 6 at 21:15 Leo Gardner 356 11 Even assuming "polyhpn" in the title is a typo for polygon , it is unclear what you mean by "the edges and sides". Aren't the side of a regular polygon the same as the edges? A regular $n$-sided polygon has $n$ edges. – hardmath Aug 6 at 21:20 3 $n$ ne...
Read more

Relationship between determinant of matrix and determinant of adjoint?

Image
Clash Royale CLAN TAG #URR8PPP up vote 2 down vote favorite We are studying adjoints in class, and I was curious if there is a relationship between the determinant of matrix A, and the determinant of the adjoint of matrix A? I assume there would be a relationship because finding the adjoint requires creating a cofactor matrix and then transposing it. linear-algebra determinant adjoint-operators share | cite | improve this question asked Nov 17 '17 at 17:32 CluelessCoder 32 5 For a square matrix $A$ of order $n$, we have $A(operatornameadj A)=(operatornameadj A)A=|A|I_n$ where $I_n$ is the identity matrix of order $n$. This should tell you about the determinant of the adjoint in terms of that of $A$ (use multiplicative property and other elementary properties of determinants). – Prasun Biswas Nov 17 '17 at 17:35 1 @CluelessCoder: see here: math.stackexchange.com/questions/516127/…...
Read more