先化简,再求值:(x-xx+1)÷(1+1x2?1),其中x=3-1

先化简,再求值:(x-xx+1)÷(1+1x2?1),其中x=3-1.
2025-05-22 02:33:59
推荐回答(1个)
回答(1):

(x-

x
x+1
)÷(1+
1
x2?1

=
x(x+1)?x
x+1
÷
x2
x2?1

=
x2
x+1
×
(x+1)(x?1)
x2

=x-1;
把x=
3
-1代入上式得:
x-1=
3
-1-1=
3
?2