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[函数] 一眼看尽`y=\frac {2^x-1}{2^x+1}`的值域

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isee posted 2021-8-13 22:34 |Read mode
函数`f(x)=\dfrac {2^x-1}{2^x+1}`的值域为__`(-1,1)`__.

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original poster isee posted 2021-8-23 23:53
回复 1# isee

奇函数,只讨论`x>0`时即可

    \[f(x)=1-\frac 2{2^x-1}\in ( 0,1).\]

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