Problem

Problem

Let ff be a real valued function defined by f(x)=ex−e−∣x∣ex+e∣x∣f(x) = \frac{e^x - e^{-|x|}}{e^x + e^{|x|}}, then the range of f(x)f(x) is: (a) RR (b) [0,1][0, 1] (c) [0,1)[0, 1) (d) [0,12)\left[0, \frac{1}{2}\right)
Intuitive explanation

The key is to recognize that this function's behavior splits into two cases based on the sign of xx, and then use symmetry to understand its full range. For x≥0x \geq 0, the absolute value simplifies nicely; for x<0x < 0, you get a different expression. Once you simplify both pieces, check whether ff is odd or even—this symmetry will tell you that if one side covers [0,a)[0, a), the other covers (−a,0](-a, 0], giving you the complete range without evaluating limits separately.

Intuitive explanation

The key is to recognize that this function's behavior splits into two cases based on the sign of xx, and then use symmetry to understand its full range. For x≥0x \geq 0, the absolute value simplifies nicely; for x<0x < 0, you get a different expression. Once you simplify both pieces, check whether ff is odd or even—this symmetry will tell you that if one side covers [0,a)[0, a), the other covers (−a,0](-a, 0], giving you the complete range without evaluating limits separately.

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