If I have the equation $$y'' +\sin\left(\frac{1}{x}\right)y = 0$$ and I approximate $\sin(\frac1x)$ as $\frac1x$, how would I get epsilon squared in front of the first term (which is required for WKB form)?
I have tried defining $\delta X=\frac1x$, but that doesn't help at all. Any help would be much appreciated. Thanks!