初中数学，先化简，再求值。

Question

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Answer 1

如下图：

Answer 2

[(x²-1)/(x+2)] ÷ [1/(x+2) - 1]
= [(x+1)(x-1)/(x+2)] ÷ [-(x-1)/(x+2)]
= -(x+1)

当x =3时，
原式 = -4

Answer 3

解：原式=(x-1)(x+1)/(X+2)*-(x+2)/x+1
=1-x
=1-3=-2

Answer 4

原式=（x^2-1/X
+2）/(1-x/x+2）=（-1）/（x+1） 代入x 所以原式等于-1/4

Answer 5

答案是-2

Answer 6

结果是﹣2