CHO X2+Y2+Z2 =XY XZ YZ+ + . CH NG MINH R NG X = Y = ZỨ Ằ­­­­­­­­­­­­­...

Bài 6: Cho x

²

+y

²

+z

²

=xy xz yz+ + . ch ng minh r ng x = y = zứ ằ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­Đ  7Ề  (Đ  KI M TRA HKI_NĂM H C: 2013­2014)Ề Ể Ọ