Differential equation, confused on directions, F(x,y)?

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Homework Help Overview

The discussion revolves around a differential equation problem involving implicit general solutions and the identification of related functions. The original poster expresses confusion regarding the instructions and the expected format for the solution.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the interpretation of the implicit general solution and the need to express the solution in a specific form. Questions arise about the correctness of the original poster's work and the implications of the instructions provided.

Discussion Status

Some participants offer guidance on how to approach the problem, suggesting ways to identify the functions G(x) and H(y) from the implicit solution. There is acknowledgment of the original poster's confusion, but no consensus on the correct answer is reached.

Contextual Notes

Participants note the absence of initial conditions and the ambiguity in the instructions regarding the expected format for the solution. The original poster's work is critiqued for potential errors in variable substitution.

mr_coffee
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Hello everyone, I am confused on what they are wanting me to do here on this problem:
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/8e/03f256344c773f4cb31a6c00deae771.png
has an implicit general solution of the form
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/46/676cc60ad18cc49904f5f4ac4fa61e1.png
In fact, because the differential equation is separable, we can define the solution curve implicitly by a function in the form
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/82/62c381e72069d44ef291f5391ed7871.png
Find such a solution and then give the related functions requested.
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/57/f15a6cea760ce4906a6ec16f9d29451.png
here is my work, i think they wanted me to do, they gave no intial condition so i solved for C:
http://img39.imageshack.us/img39/1227/lastscan5vx.jpg

but it was incorrect :cry:
 
Last edited by a moderator:
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Well what is supposed to be the correct answer? I can't see much wrong with what you've done.

Edit: You seem to have replaced the y with x after the integration of the exponential.
 
Last edited:
thats a good question, it doesn't tell me. it will tell me if i get it right, not if i get it wrong. Whats this implicit general solution stuff do i have to take partial derivatives or somthing?
 
WHY do you keep writing \frac{1}{e^{-2x}}? Surely you know that \frac{1}{e^{-2x}}= e^{2x}

Your instructions were to write the answer as F(x,y)= K and then write it as F(x,y)= G(x,y)+ H(x,y)= K

You already have 5e2x- arcsin(x/2)= K. Can't you just look at that and pick G and H?
 
Going from the second line to the third line your "y" became an "x". As far as what they want:

mr_coffee said:
Hello everyone, I am confused on what they are wanting me to do here on this problem:
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/8e/03f256344c773f4cb31a6c00deae771.png
has an implicit general solution of the form
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/46/676cc60ad18cc49904f5f4ac4fa61e1.png
In fact, because the differential equation is separable, we can define the solution curve implicitly by a function in the form
http://cwcsrv11.cwc.psu.edu/webwork2_files/tmp/equations/82/62c381e72069d44ef291f5391ed7871.png
Find such a solution and then give the related functions requested.

They asked for F(x,y)=G(x)+H(y)=K

So "Find such a solution" is satisfied by F(x,y)=-\mbox{arcsin}\left( \frac{x}{2}\right) + 5e^{2y} = K

but the answer they want is "give the related functions requested"

so try G(x)= -\mbox{arcsin}\left( \frac{x}{2}\right) \mbox{ and }H(y)= 5e^{2y}
 
Last edited by a moderator:
Ahhh, thanks so much everyone it was correct. weee
 

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