Electronic Journal of Differential Equations, Vol. 2011 (2011), No. 165, pp. 1-8. Title: Consequences of Talenti's inequality becoming equality Authors: Behrouz Emamizadeh (Xian Jiaotong-Liverpool Univ., China) Mohsen Zivari-Rezapour (Shahid Chamran Univ., Ahvaz, Iran) Abstract: In this article, we consider the case of equality in a well known inequality for the p-Laplacian due to Giorgio Talenti. Our approach seems to be simpler than the one by Kesavan [6]. We use a result from rearrangement optimization to prove the main result in this article. Some physical interpretations are also presented. Submitted June 14, 2011. Published December 13, 2011. Math Subject Classifications: 35J62, 35P30, 35Q74, 35A99, 49J20. Key Words: Talenti's inequality; p-Laplacian operator; elastic membrane; rearrangement maximization; unique optimal solution.