How can one solve $yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A$? [closed]












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How can one solve the second order nonlinear differential equation $yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A$? Here, $A,b,c$ are constants and $y(t)$ is a function.










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closed as off-topic by Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL Dec 31 '18 at 7:08


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.
















  • $begingroup$
    I added mathjax to the post, and removed the second paragraph which I thought was unclear. If you think the second paragraph was important, please do put it back with an edit, making it clearer what you meant.
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    – YiFan
    Dec 31 '18 at 2:05
















-1












$begingroup$


How can one solve the second order nonlinear differential equation $yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A$? Here, $A,b,c$ are constants and $y(t)$ is a function.










share|cite|improve this question











$endgroup$



closed as off-topic by Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL Dec 31 '18 at 7:08


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.
















  • $begingroup$
    I added mathjax to the post, and removed the second paragraph which I thought was unclear. If you think the second paragraph was important, please do put it back with an edit, making it clearer what you meant.
    $endgroup$
    – YiFan
    Dec 31 '18 at 2:05














-1












-1








-1


1



$begingroup$


How can one solve the second order nonlinear differential equation $yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A$? Here, $A,b,c$ are constants and $y(t)$ is a function.










share|cite|improve this question











$endgroup$




How can one solve the second order nonlinear differential equation $yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A$? Here, $A,b,c$ are constants and $y(t)$ is a function.







ordinary-differential-equations






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edited Dec 31 '18 at 2:04









YiFan

4,7861727




4,7861727










asked Dec 31 '18 at 1:54









alaloushalaloush

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61




closed as off-topic by Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL Dec 31 '18 at 7:08


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.







closed as off-topic by Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL Dec 31 '18 at 7:08


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Eevee Trainer, Abcd, Dylan, Lee David Chung Lin, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.












  • $begingroup$
    I added mathjax to the post, and removed the second paragraph which I thought was unclear. If you think the second paragraph was important, please do put it back with an edit, making it clearer what you meant.
    $endgroup$
    – YiFan
    Dec 31 '18 at 2:05


















  • $begingroup$
    I added mathjax to the post, and removed the second paragraph which I thought was unclear. If you think the second paragraph was important, please do put it back with an edit, making it clearer what you meant.
    $endgroup$
    – YiFan
    Dec 31 '18 at 2:05
















$begingroup$
I added mathjax to the post, and removed the second paragraph which I thought was unclear. If you think the second paragraph was important, please do put it back with an edit, making it clearer what you meant.
$endgroup$
– YiFan
Dec 31 '18 at 2:05




$begingroup$
I added mathjax to the post, and removed the second paragraph which I thought was unclear. If you think the second paragraph was important, please do put it back with an edit, making it clearer what you meant.
$endgroup$
– YiFan
Dec 31 '18 at 2:05










1 Answer
1






active

oldest

votes


















1












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Since it's autonomous, you can write this as a first order equation for $y'$ in terms of $y$. You then get solutions



$$ int ^{y left( x right) }!{frac {sqrt {b-1}}{sqrt {2,c
left( b-1 right) {s}+ left( b-1 right) {s}^{2}+C
left( b-1 right) {s}^{1-b}+2,A}}}{ds}=Bpm x
$$

where $B$ and $C$ are arbitrary constants.



I would expect that for most values of $b$ this can not be done in "closed form".






share|cite|improve this answer











$endgroup$













  • $begingroup$
    thanks @Robert Israel
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:34










  • $begingroup$
    Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:45










  • $begingroup$
    @Robert Israel Can you provide me some more info about how you arrived at this integral?
    $endgroup$
    – cgiovanardi
    Dec 31 '18 at 17:39










  • $begingroup$
    @cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
    $endgroup$
    – alaloush
    Dec 31 '18 at 19:43




















1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

Since it's autonomous, you can write this as a first order equation for $y'$ in terms of $y$. You then get solutions



$$ int ^{y left( x right) }!{frac {sqrt {b-1}}{sqrt {2,c
left( b-1 right) {s}+ left( b-1 right) {s}^{2}+C
left( b-1 right) {s}^{1-b}+2,A}}}{ds}=Bpm x
$$

where $B$ and $C$ are arbitrary constants.



I would expect that for most values of $b$ this can not be done in "closed form".






share|cite|improve this answer











$endgroup$













  • $begingroup$
    thanks @Robert Israel
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:34










  • $begingroup$
    Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:45










  • $begingroup$
    @Robert Israel Can you provide me some more info about how you arrived at this integral?
    $endgroup$
    – cgiovanardi
    Dec 31 '18 at 17:39










  • $begingroup$
    @cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
    $endgroup$
    – alaloush
    Dec 31 '18 at 19:43


















1












$begingroup$

Since it's autonomous, you can write this as a first order equation for $y'$ in terms of $y$. You then get solutions



$$ int ^{y left( x right) }!{frac {sqrt {b-1}}{sqrt {2,c
left( b-1 right) {s}+ left( b-1 right) {s}^{2}+C
left( b-1 right) {s}^{1-b}+2,A}}}{ds}=Bpm x
$$

where $B$ and $C$ are arbitrary constants.



I would expect that for most values of $b$ this can not be done in "closed form".






share|cite|improve this answer











$endgroup$













  • $begingroup$
    thanks @Robert Israel
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:34










  • $begingroup$
    Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:45










  • $begingroup$
    @Robert Israel Can you provide me some more info about how you arrived at this integral?
    $endgroup$
    – cgiovanardi
    Dec 31 '18 at 17:39










  • $begingroup$
    @cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
    $endgroup$
    – alaloush
    Dec 31 '18 at 19:43
















1












1








1





$begingroup$

Since it's autonomous, you can write this as a first order equation for $y'$ in terms of $y$. You then get solutions



$$ int ^{y left( x right) }!{frac {sqrt {b-1}}{sqrt {2,c
left( b-1 right) {s}+ left( b-1 right) {s}^{2}+C
left( b-1 right) {s}^{1-b}+2,A}}}{ds}=Bpm x
$$

where $B$ and $C$ are arbitrary constants.



I would expect that for most values of $b$ this can not be done in "closed form".






share|cite|improve this answer











$endgroup$



Since it's autonomous, you can write this as a first order equation for $y'$ in terms of $y$. You then get solutions



$$ int ^{y left( x right) }!{frac {sqrt {b-1}}{sqrt {2,c
left( b-1 right) {s}+ left( b-1 right) {s}^{2}+C
left( b-1 right) {s}^{1-b}+2,A}}}{ds}=Bpm x
$$

where $B$ and $C$ are arbitrary constants.



I would expect that for most values of $b$ this can not be done in "closed form".







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Dec 31 '18 at 5:33

























answered Dec 31 '18 at 2:23









Robert IsraelRobert Israel

329k23217470




329k23217470












  • $begingroup$
    thanks @Robert Israel
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:34










  • $begingroup$
    Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:45










  • $begingroup$
    @Robert Israel Can you provide me some more info about how you arrived at this integral?
    $endgroup$
    – cgiovanardi
    Dec 31 '18 at 17:39










  • $begingroup$
    @cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
    $endgroup$
    – alaloush
    Dec 31 '18 at 19:43




















  • $begingroup$
    thanks @Robert Israel
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:34










  • $begingroup$
    Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
    $endgroup$
    – alaloush
    Dec 31 '18 at 12:45










  • $begingroup$
    @Robert Israel Can you provide me some more info about how you arrived at this integral?
    $endgroup$
    – cgiovanardi
    Dec 31 '18 at 17:39










  • $begingroup$
    @cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
    $endgroup$
    – alaloush
    Dec 31 '18 at 19:43


















$begingroup$
thanks @Robert Israel
$endgroup$
– alaloush
Dec 31 '18 at 12:34




$begingroup$
thanks @Robert Israel
$endgroup$
– alaloush
Dec 31 '18 at 12:34












$begingroup$
Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
$endgroup$
– alaloush
Dec 31 '18 at 12:45




$begingroup$
Thank you Mr. @Robert Israel But I want to write the equation as follows (yy')^2 = F(y); F(y) = {y^4} + 2c{y^3} + A{y^2} + B{y^{3 - b}} How can I do this by once integrating this equation yy''+frac12(b-1)(y')^2 -frac12(b+1)y^2-bcy =A
$endgroup$
– alaloush
Dec 31 '18 at 12:45












$begingroup$
@Robert Israel Can you provide me some more info about how you arrived at this integral?
$endgroup$
– cgiovanardi
Dec 31 '18 at 17:39




$begingroup$
@Robert Israel Can you provide me some more info about how you arrived at this integral?
$endgroup$
– cgiovanardi
Dec 31 '18 at 17:39












$begingroup$
@cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
$endgroup$
– alaloush
Dec 31 '18 at 19:43






$begingroup$
@cgiovanardi you can arrived this integral by using Maple [> y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0; [> dsolve(y(x)*(diff(y(x), x, x, x))+b*(diff(y(x), x))*(diff(y(x), x, x))-(b+1)*y(x)*(diff(y(x), x))-bc*(diff(y(x), x)) = 0, {y(x)}); [>
$endgroup$
– alaloush
Dec 31 '18 at 19:43





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