The range of the function f(x) = x2/(1 + x2) is:
2018
The range of the function f(x) = x2/(1 + x2) is:
- A.
(- ∞, + ∞ )
- B.
(0, ∞)
- C.
(-∞, 0)
- D.
(0, 1)
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Correct answer: D
Analyze the expression:
$$f(x) = \frac{x^2}{1 + x^2}$$
Determine the Minimum Value:
Because x2 is a squared term, its value can never be negative for any real number x. The smallest possible value x2 can achieve is 0 (when x = 0).
$$f(0) = \frac{0^2}{1 + 0^2} = 0$$
Therefore, the minimum value of the function is 0, and it is inclusive (the function actually reaches 0).
Determine the Maximum Value:
For any real number x, the numerator (x2) will always be exactly 1 less than the denominator (1 + x2).
Since the numerator is strictly smaller than the denominator, the value of the fraction must always be less than 1.
As x grows towards infinity, the +1 in the denominator becomes negligible, and the fraction approaches $1$ but never quite touches it. This means 1 is an exclusive upper bound.
Combining these insights, the exact mathematical range is [0, 1).