Let the function $f ( x ) = \frac { x } { x ^ { 2 } + 1 }$ a) ( 0.5 points) Check whether $f ( x )$ satisfies the hypotheses of Bolzano's Theorem on the interval $[ - 1,1 ]$ b) (1 point) Calculate and classify the relative extrema of $f ( x )$ in $\mathbb { R }$. c) (1 point) Determine the area between the graph of the function $f ( x )$ and the x-axis on the interval $[ - 1,1 ]$.