If $[F(x)]^{100} = int_{0}^{x} (F(t))^{100} frac{dt}{1+sin t}$ then find $F(x)$












5












$begingroup$



If $[F(x)]^{100} = int_{0}^{x} (F(t))^{100} frac{dt}{1+sin t}$ then find $F(x)$.




My attempt



Differentiating both sides,



$$100[F(x)]^{99} frac{d F(x)}{dx} = frac{F(x)^{100}}{1 + sin x}$$
then
$$frac{d F(x)}{F(x)} = frac{dx}{100(1+sin x)}$$
and
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)}$$
$$log F(x) = -1/(50+50 tan (x/2))$$
Hence
$$F(x) = exp(-1/(50+50tan (x/2))$$
But, I am not getting my answer right. Where did I go wrong?






calculus







share|cite|improve this question











$endgroup$












  • $begingroup$
    I think just the multiplicative constant is ommited.
    $endgroup$
    – user376343
    Jan 1 at 13:18






  • 1




    $begingroup$
    Actually, there is printing mistake in my answer key.
    $endgroup$
    – Mathsaddict
    Jan 1 at 13:26


















5












$begingroup$



If $[F(x)]^{100} = int_{0}^{x} (F(t))^{100} frac{dt}{1+sin t}$ then find $F(x)$.




My attempt



Differentiating both sides,



$$100[F(x)]^{99} frac{d F(x)}{dx} = frac{F(x)^{100}}{1 + sin x}$$
then
$$frac{d F(x)}{F(x)} = frac{dx}{100(1+sin x)}$$
and
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)}$$
$$log F(x) = -1/(50+50 tan (x/2))$$
Hence
$$F(x) = exp(-1/(50+50tan (x/2))$$
But, I am not getting my answer right. Where did I go wrong?






calculus







share|cite|improve this question











$endgroup$












  • $begingroup$
    I think just the multiplicative constant is ommited.
    $endgroup$
    – user376343
    Jan 1 at 13:18






  • 1




    $begingroup$
    Actually, there is printing mistake in my answer key.
    $endgroup$
    – Mathsaddict
    Jan 1 at 13:26
















5












5








5


0



$begingroup$



If $[F(x)]^{100} = int_{0}^{x} (F(t))^{100} frac{dt}{1+sin t}$ then find $F(x)$.




My attempt



Differentiating both sides,



$$100[F(x)]^{99} frac{d F(x)}{dx} = frac{F(x)^{100}}{1 + sin x}$$
then
$$frac{d F(x)}{F(x)} = frac{dx}{100(1+sin x)}$$
and
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)}$$
$$log F(x) = -1/(50+50 tan (x/2))$$
Hence
$$F(x) = exp(-1/(50+50tan (x/2))$$
But, I am not getting my answer right. Where did I go wrong?






calculus







share|cite|improve this question











$endgroup$





If $[F(x)]^{100} = int_{0}^{x} (F(t))^{100} frac{dt}{1+sin t}$ then find $F(x)$.




My attempt



Differentiating both sides,



$$100[F(x)]^{99} frac{d F(x)}{dx} = frac{F(x)^{100}}{1 + sin x}$$
then
$$frac{d F(x)}{F(x)} = frac{dx}{100(1+sin x)}$$
and
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)}$$
$$log F(x) = -1/(50+50 tan (x/2))$$
Hence
$$F(x) = exp(-1/(50+50tan (x/2))$$
But, I am not getting my answer right. Where did I go wrong?






calculus




calculus






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 1 at 13:15









Robert Z

94.2k1061132




94.2k1061132










asked Jan 1 at 12:49









MathsaddictMathsaddict

2908




2908












  • $begingroup$
    I think just the multiplicative constant is ommited.
    $endgroup$
    – user376343
    Jan 1 at 13:18






  • 1




    $begingroup$
    Actually, there is printing mistake in my answer key.
    $endgroup$
    – Mathsaddict
    Jan 1 at 13:26




















  • $begingroup$
    I think just the multiplicative constant is ommited.
    $endgroup$
    – user376343
    Jan 1 at 13:18






  • 1




    $begingroup$
    Actually, there is printing mistake in my answer key.
    $endgroup$
    – Mathsaddict
    Jan 1 at 13:26


















$begingroup$
I think just the multiplicative constant is ommited.
$endgroup$
– user376343
Jan 1 at 13:18




$begingroup$
I think just the multiplicative constant is ommited.
$endgroup$
– user376343
Jan 1 at 13:18




1




1




$begingroup$
Actually, there is printing mistake in my answer key.
$endgroup$
– Mathsaddict
Jan 1 at 13:26






$begingroup$
Actually, there is printing mistake in my answer key.
$endgroup$
– Mathsaddict
Jan 1 at 13:26












1 Answer
1






active

oldest

votes


















2












$begingroup$

Note that we have the stationary solution $F(x)equiv 0$. If $F(x)not=0$ then, by separation of variables,
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)} $$
which implies
$$log |F(x)| = -frac{1}{50(1+tan (x/2))}+c.$$
and for $xin (-pi,pi)$,
$$F(x)=Cexpleft(-frac{1}{50(1+tan (x/2))}right).$$
Moreover by assumption, it seems that $F(0)=0$.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    Also, $F(x)equiv 0$ should work too.
    $endgroup$
    – InequalitiesEverywhere
    Jan 1 at 12:54










  • $begingroup$
    @InequalitiesEverywhere Yes, you are right that is the stationary solution.
    $endgroup$
    – Robert Z
    Jan 1 at 13:00











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%2f3058457%2fif-fx100-int-0x-ft100-fracdt1-sin-t-then-find-fx%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









2












$begingroup$

Note that we have the stationary solution $F(x)equiv 0$. If $F(x)not=0$ then, by separation of variables,
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)} $$
which implies
$$log |F(x)| = -frac{1}{50(1+tan (x/2))}+c.$$
and for $xin (-pi,pi)$,
$$F(x)=Cexpleft(-frac{1}{50(1+tan (x/2))}right).$$
Moreover by assumption, it seems that $F(0)=0$.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    Also, $F(x)equiv 0$ should work too.
    $endgroup$
    – InequalitiesEverywhere
    Jan 1 at 12:54










  • $begingroup$
    @InequalitiesEverywhere Yes, you are right that is the stationary solution.
    $endgroup$
    – Robert Z
    Jan 1 at 13:00
















2












$begingroup$

Note that we have the stationary solution $F(x)equiv 0$. If $F(x)not=0$ then, by separation of variables,
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)} $$
which implies
$$log |F(x)| = -frac{1}{50(1+tan (x/2))}+c.$$
and for $xin (-pi,pi)$,
$$F(x)=Cexpleft(-frac{1}{50(1+tan (x/2))}right).$$
Moreover by assumption, it seems that $F(0)=0$.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    Also, $F(x)equiv 0$ should work too.
    $endgroup$
    – InequalitiesEverywhere
    Jan 1 at 12:54










  • $begingroup$
    @InequalitiesEverywhere Yes, you are right that is the stationary solution.
    $endgroup$
    – Robert Z
    Jan 1 at 13:00














2












2








2





$begingroup$

Note that we have the stationary solution $F(x)equiv 0$. If $F(x)not=0$ then, by separation of variables,
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)} $$
which implies
$$log |F(x)| = -frac{1}{50(1+tan (x/2))}+c.$$
and for $xin (-pi,pi)$,
$$F(x)=Cexpleft(-frac{1}{50(1+tan (x/2))}right).$$
Moreover by assumption, it seems that $F(0)=0$.






share|cite|improve this answer











$endgroup$



Note that we have the stationary solution $F(x)equiv 0$. If $F(x)not=0$ then, by separation of variables,
$$int frac{d F(x)}{F(x)} = int frac{dx}{100(1+sin x)} $$
which implies
$$log |F(x)| = -frac{1}{50(1+tan (x/2))}+c.$$
and for $xin (-pi,pi)$,
$$F(x)=Cexpleft(-frac{1}{50(1+tan (x/2))}right).$$
Moreover by assumption, it seems that $F(0)=0$.







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Jan 1 at 13:11

























answered Jan 1 at 12:51









Robert ZRobert Z

94.2k1061132




94.2k1061132












  • $begingroup$
    Also, $F(x)equiv 0$ should work too.
    $endgroup$
    – InequalitiesEverywhere
    Jan 1 at 12:54










  • $begingroup$
    @InequalitiesEverywhere Yes, you are right that is the stationary solution.
    $endgroup$
    – Robert Z
    Jan 1 at 13:00


















  • $begingroup$
    Also, $F(x)equiv 0$ should work too.
    $endgroup$
    – InequalitiesEverywhere
    Jan 1 at 12:54










  • $begingroup$
    @InequalitiesEverywhere Yes, you are right that is the stationary solution.
    $endgroup$
    – Robert Z
    Jan 1 at 13:00
















$begingroup$
Also, $F(x)equiv 0$ should work too.
$endgroup$
– InequalitiesEverywhere
Jan 1 at 12:54




$begingroup$
Also, $F(x)equiv 0$ should work too.
$endgroup$
– InequalitiesEverywhere
Jan 1 at 12:54












$begingroup$
@InequalitiesEverywhere Yes, you are right that is the stationary solution.
$endgroup$
– Robert Z
Jan 1 at 13:00




$begingroup$
@InequalitiesEverywhere Yes, you are right that is the stationary solution.
$endgroup$
– Robert Z
Jan 1 at 13:00


















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%2f3058457%2fif-fx100-int-0x-ft100-fracdt1-sin-t-then-find-fx%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

Can a sorcerer learn a 5th-level spell early by creating spell slots using the Font of Magic feature?

Image
28 6 $begingroup$ Per the Font of Magic feature, sorcerer can use Flexible Casting to create 5th-level spell slots at level 7, even though they are not typically available until level 9. You can transform unexpended sorcery points into one spell slot as a bonus action on your turn. The Creating Spell Slots table shows the cost of creating a spell slot of [5th level is 7] If such a sorcerer levels up while still having this 5th-level spell slot, can they choose a 5th-level spell as the spell they gain upon levelling up? The Spellcasting feature states: Additionally, when you gain a level in this class, you can choose one of the sorcerer spells you know and replace it with another spell from the sorcerer spell list, which also must be of a level for which you have spell slots.
Read more

Does disintegrating a polymorphed enemy still kill it after the 2018 errata?

Image
up vote 13 down vote favorite 1 After the 2018 errata, the disintegrate spell description now reads: A creature targeted by this spell must make a Dexterity saving throw. On a failed save, the target takes 10d6 + 40 force damage. The target is disintegrated if this damage leaves it with 0 hit points. If you were to polymorph an enemy into a rat and then disintegrate it, would the enemy be disintegrated or would it just return to its original form? I know that for Druids, it’s not an instant kill anymore, but is this the case for polymorph as well? dnd-5e spells polymorph errata share | improve this question edited 18 hours ago
Read more

A Topological Invariant for $pi_3(U(n))$

Image
3 3 $begingroup$ Recently, I saw a construction of topological invariant for $pi_3(U(n))$ with $ngeq 2$ : $$ N=frac{1}{24pi^2}int_{S^3} d^3x epsilon^{ijk} Tr[(U^{-1}partial_{x_i}U)(U^{-1}partial_{x_j}U)(U^{-1}partial_{x_k}U)] , $$ where $Uin U(n)$ depends on $boldsymbol{x}=(x_1,x_2,x_3)in S^3$ , $epsilon^{ijk}$ is the Levi-Civita symbol, $i,j,k=1,2,3$ , and the duplicated indexes are summed over. It is claimed that $N$ is an integer, but why? Update 02/02/2019 I think I got an argument for $n=2$ . In this case, $U=e^{i varphi} q$ with $qin SU(2)$ . Due to the trace and the Levi-Civita symbol in $N$ , $varphi$ does not contribute to $N$ . As $Tr[q^{dagger}partial_i q]=0$ and $(q^{dagger}partial_i q)^{dagger}=-q^{dagger}partial_i q$ , $q^{dagger}partial_i q$ in geneeral has the form $q^{dagger}partia
Read more