20102010 2010 2010 1 1+ + + + + +XY X + YZ Y + XZ Z =HD

Bài 19: Cho xyz=2010, CMR: 2010

2010 2010 2010 1 1

+ + + + + +

xy x + yz y + xz z =

HD :

2

x yz y z

VT = xy x yz xyz + yz y xyz + xz z =

2

1

1