Bernoulli Differential Equation

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SUMMARY

The discussion centers on solving the Bernoulli differential equation represented by the equation 3dy/dx + y = (1 - 2x)y^4. The solution process involves substituting w = 1/y^3, leading to the transformed equation w' - w = 2x - 1. A mistake in integration was identified, which affected the final expression for y^3. The correct solution, as confirmed by Wolfram Alpha, is y^3 = -1/(-c*e^x + 2x + 1).

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bioblade
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Homework Statement



Solve: 3dy/dx+y=(1-2x)y^4

Homework Equations



None, really.

The Attempt at a Solution



y'+y/3=((1-2x)/3)y^4

y'/y^4+1/3y^3=(1-2x)/3

w=1/y^3

w'=(-3/y^4)y'

w'/-3+w/3=(1-2x)/3

w'-w=2x-1

e^int(-dx)=e^-x

e^(-x)*w=-e^-x(2x-1)+c

w=1-2x+c*e^x

y^3=1/(1-2x+c*e^x)

wolfram alpha says it should be -1/(-c*e^x+2x+1) though. What did I do wrong?
 
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bioblade said:

Homework Statement



Solve: 3dy/dx+y=(1-2x)y^4

Homework Equations



None, really.

The Attempt at a Solution



y'+y/3=((1-2x)/3)y^4

y'/y^4+1/3y^3=(1-2x)/3

w=1/y^3

w'=(-3/y^4)y'

w'/-3+w/3=(1-2x)/3

w'-w=2x-1

e^int(-dx)=e^-x

e^(-x)*w=-e^-x(2x-1)+c

Right there where you didn't show your work, you have a mistake in your integration.

w=1-2x+c*e^x

y^3=1/(1-2x+c*e^x)

wolfram alpha says it should be -1/(-c*e^x+2x+1) though. What did I do wrong?
 
Ah, I got it now. Thanks!
 

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