Question

这种不等式该怎么解 我需要详细过程

(a-1)/(a+1) 小于 1

如果a+1乘过去 两边的a就没了 怎么做啊

Answer 1

(a-1)/(a+1) < 1
则(a-1)/(a+1)-1<0
(-2)/(a+1)<0
则显然 只要a+1大于零就可以
则a>-1

Answer 2

a+1可能等于0
不能直接乘过去
利用分式函数图像双曲线

Answer 3

(a-1)/(a+1) < 1

=> (a+1 - 2)/(a+1) < 1

=> 1 - 2/(a+1) < 1

=> 1/(a+1) > 1

=> a+1 > 0 且 1 > a+1

=> -1 < a < 0

Answer 4

(a-1)/(a+1) ＜ 1
(a-1)/(a+1) - 1＜0
（a-1-a-1）/（a+1）＜0
-2/（a+1）＜0
2/（a+1）＞0
∴a+1＞0
∴a＞-1