Evaluate the following limits.

(a) $\displaystyle \lim_{ x \to \infty } \frac{3}{e^{x}+1}=$

(b) $\displaystyle \lim_{ x \to -\infty } \frac{3}{e^{x}+1} =$

[NOTE: If needed, enter INF or infinity for $\infty$ and -INF or -infinity for $-\infty$.]