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The DE $y - x \dfrac{dy}{dx} = 0$ has general solution:
A$y = cx$
B$y = c/x$
C$y = c e^x$
D$y^2 = c x$
Answer & Solution
Correct answer: A. $y = cx$
Rewrite: $dy/y = dx/x$. Integrating: $\log y = \log x + \log c$ ⇒ $y = cx$ (family of straight lines through origin).
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