MathDB
A veeeery simple inequality

Source:

October 23, 2005
inequalitiesalgebra

Problem Statement

If a,b,c,da,b,c,d are four positive reals such that abcd=1abcd= 1 , prove that (1+a)(1+b)(1+c)(1+d)16.(1+a) (1+b) (1 +c ) (1 +d ) \geq 16.