Question

化简:x/(x+1)-(x+3)/(x+1)×(x^2-1)/(x+2)^2-1,再选一个你认为运算方便的数代入求值

化简:x/(x+1)-(x+3)/(x+1)×(x^2-1)/(x+2)^2-1,再选一个你认为运算方便的数代入求值

Answer 1

2
X X+3 X -1
--- - --- * --------
2
X+1 X+1 (X+2)-1

解：
x x+3 (x+1)(x-1)
= --- - --- * ---------------
x+1 x+1 (x+2-1)(x+2+1) ===》（x+1)(x+3)

x x+3 x-1
= --- - --- * ---
x+1 x+1 x+3

x (x-3)(x-1）
= --- - ----------
x+1 (x+1)(x+3)

2 2
x(x+3)-(x-3)(x-1） ===>x +3x-x +x+3x-3
= -------------------
(x+1)(x+3)

7x-3
= ----------
(x+1)(x+3)

3
x取--- ，根为0

修改答复：怎么会这样...

7

Answer 2

x/(x+1)-(x+3)/(x+1)×(x^2-1)/(x+2)^2-1

Answer 3

1