Question

先化简后求值：已知x=

2

+1，求x+1-

x2

x-1

的值．

Answer 1

x+1-

x2

x-1

=

x-1

1

-

x2-1

x-1

=

x2-1

x-1

-

x2

x-1

=-

1

x-1

，
当x=

2

+1时，原式=-

1

2 +1-1

=-

1

2

=-

2

2

．