(b) Calculate the x-elasticities of some basic functions:
i. $\mathcal{E}_{x^a, x}(x)$ for $a \in \mathbb{R}$
ii. $\mathcal{E}_{e^x, x}(x)$
iii. $\mathcal{E}_{a^x, x}(x)$ for $a > 0$
iv. $\mathcal{E}_{\ln(x), x}(x)$
v. $\mathcal{E}_{c, x}(x)$ for $c \in \mathbb{R}$