\(y = \dfrac{x}{{4 + {x^2}}}\) trên khoảng \(( - \infty ; + \infty )\)
A.Không xác định
B.\(\mathop {\min }\limits_R f(x) = - \dfrac{1}{4};\mathop {\max }\limits_R f(x) =0\)
C.\(\mathop {\min }\limits_R f(x) = 0;\mathop {\max }\limits_R f(x) = \dfrac{1}{4}\)
D.\(\mathop {\min }\limits_R f(x) = - \dfrac{1}{4};\mathop {\max }\limits_R f(x) = \dfrac{1}{4}\)