问题
解答题
先化简，再求值
|
答案
÷x+1 x2+1
-(x+1)3 x4-1 x-3 x+1
=
•x+1 x2+1
-(x2+1)(x+1)(x-1) (x+1)3 x-3 x+1
=
-x-1 x+1 x-3 x+1
=
；2 x+1
当x=
+1时，3
原式=
=2 x+1
=2
+1+13
=2(2-2
+23
)=4-23
．3
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