In the following exercises, use direct substitution to show that each limit leads to the indeterminate form 0/0. Then, evaluate the limit.

a) lim(x → 0) (sin x / x)
b) lim(x → 1) ((x² - 1) / (x - 1))
c) lim(x → [infinity]) (eˣ / x²)
d) lim(x → 2) ((x³ - 8) / (x - 2))