this post was submitted on 14 May 2024
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  • Express y in terms of x for differential equation dy/dx=ylny

(I'm officially out of ideas again)

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[–] zkfcfbzr 3 points 6 months ago* (last edited 6 months ago)

solutionNot sure if I'd have gotten this one without Cavy's hint, I'm pretty bad with differential equations

Let z = ln(y)

Then z = dy/dx / y

dy/dx / y is the derivative of ln(y)

So we have z = d/dx ln(y), or ln(y) = d/dx ln(y)

ln(y) is its own derivative - so we must have ln(y) = e^x, which implies y = e^(e^x)