f:R→Rf : \mathbb R \to \mathbb Rf:R→R, f(x)=x1+x2f(x) = \dfrac{x}{1+x^2}f(x)=1+x2x. Then
−1≤f(x)≤1-1 \leq f(x) \leq 1−1≤f(x)≤1
−1≤f(x)≤1/2-1 \leq f(x) \leq 1/2−1≤f(x)≤1/2
−1/2≤f(x)≤1-1/2 \leq f(x) \leq 1−1/2≤f(x)≤1
−1/2≤f(x)≤1/2-1/2 \leq f(x) \leq 1/2−1/2≤f(x)≤1/2
