解;
2/(1/a+1/b)
=2/[(a+b)/ab]
=2ab/(a+b)
(a+b)/2-2ab/(a+b)
=[(a+b)²-2ab]/(a+b)
=(a-b)²/(a+b)
∵a≠b,b>0,a>0
∴(a+b)/2>2/(1/a+1/b)
解;
2/(1/a+1/b)
=2/[(a+b)/ab]
=2ab/(a+b)
(a+b)/2-2ab/(a+b)
=[(a+b)²-2ab]/(a+b)
=(a-b)²/(a+b)
∵a≠b,b>0,a>0
∴(a+b)/2>2/(1/a+1/b)