Differential Equations homework problem.

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SUMMARY

The discussion focuses on solving a Riccati equation of the form \(\frac{dy}{dx} = A(x)y^2 + B(x)y + C(x)\) using a known particular solution \(y_1(x)\). The substitution \(y = y_1 + \frac{1}{v}\) is proposed to transform the Riccati equation into a linear equation \(\frac{dv}{dx} + (B + 2Ay_1)v = -A\). A participant named Rob struggles with substituting \(y\) and its derivative \(y'\) back into the original equation to simplify it correctly. Another user advises Rob to replace \(\frac{dy_1}{dx}\) with \(A(x)y_1^2 + B(x)y_1 + C(x)\) to proceed with the solution.

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Homework Statement


The equation [tex]\frac{dy}{dx}[/tex] = A(x)y2+B(x)y+C(x) is called a Riccati equation. Suppose that one particular solution y1(x) of this equation is known. Show that the substitution

y = y1+[tex]\frac{1}{v}[/tex]

transforms the Riccati equation into the linear equation

[tex]\frac{dv}{dx}[/tex]+ (B+2Ay1)v = -A.


The Attempt at a Solution



So i know that y' = y1' - [tex]\frac{v'}{v^2}[/tex] and I have tried substituting y and y' back into the original equation in order to simplify it down to the linear equation given. Unfortunately for some reason I am not getting anywhere. Any help would be appreciated!

Thanks,
Rob

P.S. Sorry for the crappy formatting, not really sure what I am doing.
 
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tarmon.gaidon said:

Homework Statement


The equation [tex]\frac{dy}{dx}[/tex] = A(x)y2+B(x)y+C(x) is called a Riccati equation. Suppose that one particular solution y1(x) of this equation is known. Show that the substitution

y = y1+[tex]\frac{1}{v}[/tex]

transforms the Riccati equation into the linear equation

[tex]\frac{dv}{dx}[/tex]+ (B+2Ay1)v = -A.


The Attempt at a Solution



So i know that y' = y1' - [tex]\frac{v'}{v^2}[/tex] and I have tried substituting y and y' back into the original equation in order to simplify it down to the linear equation given. Unfortunately for some reason I am not getting anywhere. Any help would be appreciated!

Thanks,
Rob

P.S. Sorry for the crappy formatting, not really sure what I am doing.
When you make your substitution, the left side will be dy1/dx - v'/v. Are you remembering to replace dy1/dx by A(x)y12 + B(x)y1 + C(x)?
 

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