问题
解答题
先化简，再求值：(
|
答案
(
-4x+5 x2-1
)÷3 x-1 x+2 x2-2x+1
=[
-4x+5 (x+1)(x-1)
]•3(x+1) (x+1)(x-1) (x-1)2 x+2
=
•4x+5-3x-3 (x+1)(x-1) (x-1)2 x+2
=
•x+2 (x+1)(x-1) (x-1)2 x+2
=
；x-1 x+1
当x=3时，
原式=
=3-1 3+1
．1 2