Transfer Functions of filters
Hint 1) Your first result is 

$$
\frac{V_{out}(j\omega)}{V_{in}(j\omega)}=1 \Bigg\rvert_{\omega=0}
$$

i.e., at low frequencies you have \$V_{out} = V_{in} = 0\,dB\$ (the input signal is not attenuated).

Hint 2) For the case 

$$
\frac{V_{out}(j\omega)}{V_{in}(j\omega)}\Bigg\rvert_{\omega=\infty}
$$

use L'Hôpital's rule to evaluate the function's limit as ω tends to infinity:

$$
\lim_{\omega\rightarrow\infty} \frac{V_{out}(j\omega)}{V_{in}(j\omega)}
$$