CHO 1X+1Y+1Z= 1X+Y+Z

Câu 2 : Cho

1

x

+

1

y

+

1

z

=

1

x

+

y

+

z

. Chứng minh rằng :

1

x

2003

+

1

y

2003

+

1

z

2003

=

1

x

2003

+

y

2003

+

z

2003