设函数f {(1-x)/(1+x)}= x,则f(x)表达式为A (1+x)/(1-x) B (1+x)/(x-1) C (1-x)/(1+x)D 2x/(x+1)
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![设函数f {(1-x)/(1+x)}= x,则f(x)表达式为A (1+x)/(1-x) B (1+x)/(x-1) C (1-x)/(1+x)D 2x/(x+1)](/uploads/image/z/10351350-54-0.jpg?t=%E8%AE%BE%E5%87%BD%E6%95%B0f+%7B%281-x%29%2F%281%2Bx%29%7D%3D+x%2C%E5%88%99f%28x%29%E8%A1%A8%E8%BE%BE%E5%BC%8F%E4%B8%BAA+%281%2Bx%29%2F%281-x%29+B+%281%2Bx%29%2F%28x-1%29+C+%281-x%29%2F%281%2Bx%29D+2x%2F%28x%2B1%29)
设函数f {(1-x)/(1+x)}= x,则f(x)表达式为A (1+x)/(1-x) B (1+x)/(x-1) C (1-x)/(1+x)D 2x/(x+1)
设函数f {(1-x)/(1+x)}= x,则f(x)表达式为
A (1+x)/(1-x)
B (1+x)/(x-1)
C (1-x)/(1+x)
D 2x/(x+1)
设函数f {(1-x)/(1+x)}= x,则f(x)表达式为A (1+x)/(1-x) B (1+x)/(x-1) C (1-x)/(1+x)D 2x/(x+1)
令a=(1-x)/(1+x)
1+a=1+(1-x)/(1+x)=2/(1+x)
1+x=2/(1+a)
x=2/(1+a)-1=(1-a)/(1+a)
则f(a)=(1-a)/(1+a)
所以f(x0=(1-x)/(1+x)
选C
设(1-x)/(1+x)=y,可以求出x=(1-y)/(1+y),这就是关于x的函数,所以f(x)=(1-x)/(1+x),答案为c