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Homework Statement
So I came across one of these equations. Solve : dy/dx + y2 = 1 + x2 when y(x) = x is a particular solution.
Homework Equations
The Attempt at a Solution
So I re-arranged my equation into Riccati form : dy/dx = 1 + x2 - y2
Now I let : v = \frac{1}{y-y(x)} so that y = x + 1/v
Thus : dy/dx = -(1/v2)dv/dx + 1
Subbing these back into my equation yields :
(-1/v2)dv/dx + 1 = 1 + x2 - (1/v + x)2
Simplifying everything, I get a seperable linear equation in standard form :
dv/dx - 2xv = 1 (***)
So my integrating factor μ must satisfy :
dμ/dx = -2xμ which implies that μ = e-x2
So now my equation (***) can be re-written as :
d/dx [e-x2v] = e-x2
Integrating both sides and then expressing my integrand in terms of the error function gives me the final answer :
v = \frac{\sqrt{\pi} \space erf(x) + d}{2e^{-x^2}}
And finally plugging v back into y yields my solution :
y = x + \frac{2e^{-x^2}}{\sqrt{\pi} \space erf(x) + d}
Is this correct? This is my first try at one of these so I'm still in the not sure what I'm doing moment.
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