(n-1)s -a2 -a3 -a4.....an=a1
a1=(s-a2) +(s-a3) +(s-a4)...........(s-an)
>(n-1) [(s-a2)(s-a3)....(s-an)]1/(n-1) ........since AM > GM
similarly write other inequalities for a2 a3 a 4 and so on and then multiply u will get teh req inequality
ai>0;i=1,2,3,4.........n
(n-1)s=a1+a2+a3+a4+..............an
prove that
a1.a2a3..........an>= (n-1)n(s-a1).(s-a2).(s-a3)(s-a4).........(s-an)
(n-1)s -a2 -a3 -a4.....an=a1
a1=(s-a2) +(s-a3) +(s-a4)...........(s-an)
>(n-1) [(s-a2)(s-a3)....(s-an)]1/(n-1) ........since AM > GM
similarly write other inequalities for a2 a3 a 4 and so on and then multiply u will get teh req inequality