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**Ulysses** Hi. I have this problem, which says: The equation $\displaystyle x^2y''+pxy'+qy=0$ (p and q constants) is called Euler equation. Demonstrate that the change of variable $\displaystyle u=\ln (x)$ transforms the equation to one at constant coefficients.

I haven't done much. I just normalized the equation: $\displaystyle y''+\displaystyle\frac{p}{x}y'+\displaystyle\frac{ q}{x^2}y=0$

Then $\displaystyle P(x)=\displaystyle\frac{p}{x}$ and $\displaystyle Q(x)=\displaystyle\frac{q}{x^2}$

What should I do now? I thought instead of doing $\displaystyle x=e^u$, then $\displaystyle y''+\displaystyle\frac{p}{e^u}y'+ \displaystyle\frac{q}{e^{2u}} y=0$ may be this is the right way, cause it seems more like following the problem suggestion.