- #1
Why Does Substitution Fail in Solving Differential Equations?
- Thread starter shreddinglicks
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Homework Help Overview
The discussion revolves around solving a system of equations related to a differential equation problem, specifically focusing on the variables C1 and C2. The original poster expresses difficulty in obtaining correct values after attempting methods such as elimination and substitution.
Discussion Character
- Mixed
Approaches and Questions Raised
- Participants discuss the original poster's attempts to solve the equations through elimination and substitution, questioning the clarity of the provided information and the correctness of the substitutions made.
Discussion Status
Some participants have pointed out potential misunderstandings in the substitution process and have requested clearer presentation of the work. There is an ongoing exploration of the problem setup and the equations involved.
Contextual Notes
There are indications of confusion regarding the problem statement, including a mislabeling of the equations and the original poster's attachment being difficult to read. The original poster has acknowledged a typo in the equations presented.
- #2
SteamKing
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shreddinglicks said:
Great! What's number 13? Your attachment (which is upside down, thank you very much) has several different scribbles at the top of the page, one of which appears to be '11.'
The thread title mentions 'differential equation', but your thread talks about 'elimination and substitution', which doesn't suggest solving a DE.
Care to start over?
- #3
Mark44
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Please take the time to post your work right side up. Better yet, type your work here in the input pane as text.shreddinglicks said:
- #4
Mark44
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Please take the time to post your work right side up. If you can't be bothered to make it easy to help you, many homework helpers here will choose not to jump in.shreddinglicks said:
Better yet, type your work here in the input pane as text.
- #5
shreddinglicks
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I apologize, I posted this in haste and did not check to see if my post was upside down. I do not see how it's illegible. You will see towards the right there is a #13. The problem has two equations that are boxed in with C1 and C2. I need to solve for the two variables. I can't seem to get the correct values of C1 and C2.
y = C1e^x + C2e^x
y' = C1e^x - C2e^-x
y(-1) = 5
y'(-1) = -5
In case it's not legible.
I end up with a systems of equations after I plug in the info I am given. Which I have boxed in on the attachment.
y = C1e^x + C2e^x
y' = C1e^x - C2e^-x
y(-1) = 5
y'(-1) = -5
In case it's not legible.
I end up with a systems of equations after I plug in the info I am given. Which I have boxed in on the attachment.
- #6
- #7
Mark44
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Typo in the first equation above. It should be y = C1e^x + C2e^(-x)shreddinglicks said:
shreddinglicks said:
- #8
Mark44
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You are substituting incorrectly.
y(-1) = 5 means you should replace x by -1 and y by 5. You are doing the opposite.
Same thing in the 2nd equation.
y(-1) = 5 means you should replace x by -1 and y by 5. You are doing the opposite.
Same thing in the 2nd equation.
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