已知f(x)的定义域是【1,2】，求f(1∕x+1)的定义域

Question

如题所述

Answer 1

f(x)的定义域是【1,2】

所以
f(1∕x+1)中

1/x+1∈【1,2】
即
1<=1/x+1<=2
0<=1/x<=1
所以
x>=1
即
定义域为【1，+∞）追问

不好意思 没写清楚是f(1∕（x+1）)

追答

1<=1/(x+1)<=2
1/2<=x+1<=1
所以
-1/2<=x<=0
即
定义域为【-1/2，0】

Answer 2

1<=1/(x+1)<=2
1/2<=x+1<=1
所以
-1/2<=x<=0
即
定义域为[-1/2，0]

Answer 3

f(1/2,1/3)

Answer 4

我不会

Answer 5

1<=1/(x+1)<=2
1/2<=x+1<=1
所以
-1/2<=x<=0
即
定珐单粹竿诔放达虱惮僵义域为[-1/2，0]