What am I doing wrong? Solving first order DE's

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SUMMARY

The discussion focuses on solving the first-order differential equation given by ty' + (t+1)y = t with the initial condition y(ln 2) = 1. The user attempted to solve it using the integrating factor method, deriving the integrating factor u(t) = t*e^t. However, the solution derived does not match the book's answer, which is y = (t - 1 + 2e^(-t)) / t. The discrepancy arises from an error in the integration or application of the initial condition.

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What am I doing wrong?? Solving first order DE's

Homework Statement


Solve the following first order differential equation:
ty' + (t+1)y = t; y(ln 2) = 1, t > 0


Homework Equations





The Attempt at a Solution


I try to solve this using the method of integrating factors. First I divide the equation by t to get:

y' + [(t+1)/t]y = 1

So following from this I find the integrating factor u(t) = t*e^t

So to solve this I just take an integral of both sides of equations to get:

y*t*e^t = e^t(t-1) + C

Is this right? I now just have to solve for y, and then plug in for the initial values to get C. But the answer I get does not match my book's answer! Can anyone show me what I did wrong here? Thanks
 
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DWill said:
So to solve this I just take an integral of both sides of equations to get:

y*t*e^t = e^t(t-1) + C

Is this right? I now just have to solve for y, and then plug in for the initial values to get C. But the answer I get does not match my book's answer! Can anyone show me what I did wrong here? Thanks

I get the same. What is the book's answer?
 


The book says the answer is:

y = (t - 1 + 2e^(-t)) / t, where t cannot equal 0.
 

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