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Solve x²y''+4xy'+2y=eˣ
Short answer
Recognise left side as (x²y)''. Integrate twice: (x²y)' = eˣ + c₁, then x²y = eˣ + c₁x + c₂. Hence general solution: y = eˣ/x² + c₁/x + c₂/x².
Solve the differential equation x² d²y/dx² + 4x dy/dx + 2y = eˣ.
x² y'' + 4x y' + 2y = eˣ
Quick method: recognise the left side
Since (x²y)'' = x²y'' + 4xy' + 2y, the equation is
d²(x²y)/dx² = eˣ
Integrate twice:
d(x²y)/dx = eˣ + c₁ x²y = eˣ + c₁x + c₂
y = eˣ/x² + c₁/x + c₂/x²
Check by the standard (Cauchy–Euler) method
Put z = log x, D = d/dz: (D(D − 1) + 4D + 2)y = e^(eᶻ), i.e. (D + 1)(D + 2)y = e^(eᶻ).
CF = c₁e^(−z) + c₂e^(−2z) = c₁/x + c₂/x², which matches the terms above. The particular integral gives eˣ/x², so the general solution is the same.
✓ Answer checked by Claude Opus 5.5 (high effort)
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