Evaluate the following limits. If needed, enter INF for $\infty$ and MINF for $-\infty$.

(a) $$\lim_{ x \rightarrow \infty } \frac {\sqrt{ 4 + 7 x^2 } }{ 3 + 9 x } =$$
The corresponding horizontal asymptote has equation
$y =$
(Type in DNE if there is no corresponding horizontal asymptote.)

(b) $$\lim_{ x \rightarrow -\infty } \frac {\sqrt{ 4 + 7 x^2 } }{ 3 + 9 x } =$$
The corresponding horizontal asymptote has equation
$y =$
(Type in DNE if there is no corresponding horizontal asymptote.)