Using the graph of the rational function $y = f(x)$ given in the figure below, evaluate the limits. If you need to enter $\infty$ or $- \infty$, type INFINITY or -INFINITY.

(a) $\displaystyle \lim_{x \to \infty} f(x) =$ help (limits)

(b) $\displaystyle \lim_{x \to - \infty} f(x) =$ help (limits)

(c) $\displaystyle \lim_{x \to 1^+} f(x) =$ help (limits)

(d) $\displaystyle \lim_{x \to 1^-} f(x) =$ help (limits)