Question

若x，y是实数，且y=

x-1

+

1-x

+

1

2

．求

1-y

x-2

的值．

Answer 1

由题意得：

x-1≥0 1-x≥0

，解得x=1，
把x=1代入得y=

1

2

所以

1-y

x-2

=

1- 1 2

1-2

=-

2

2

．