26D15.

The aim of this short note is to establish an integral inequality and its reverse which give an affirmative answer to an open problem posed by QUOC ANH NGO, DU DUC THANG, TRANT TAT DAT, and DANG ANH TUAN, in the paper [Notes on an integral inequality, J. Ineq. Pure and Appl. Math., 7(4)(2006), Art. 120.];