27b On the Elliptic Equation $\triangle u + |x|^\ell K(x)u^{p^*}=0$ in $R^n$ Jann-Long Chern In this paper, we consider the elliptic equation $\triangle u + |x|^\ell K(x) u^{p^*}=0$ in $R^n, n\ge 3$, where $\ell > -2$, $K$ is a suitable function on $R^n$ and $p^*=\frac {n+2+2\ell}{n-2}$. We obtain a necessary and sufficient condition for the existence of a positive radial solution $u=u(|x|)$ with the asymptotic behavior $\lim\limits_{r\to \infty} r^{n-2} u(r)=\b > 0$. This condition makes contact with the Kazdan-Warner obstruction. We also give several sufficient conditions for solvability extending several earlier results. 0