Given the points $(2, 9)$ and $(4, 324)$:

1. Write the equation of a line that passes through them.

   Hint (a):

   Use $y = mx + b$ and the given points to solve for $m$ and $b$.

   Step 1(a):

   $9 = 2m + b$
   $324 = 4m + b$

2. Write the equation of an exponential function with an asymptote at $y = 0$ that passes through them.

   Hint (b):

   Use $y = a(b)^x$ and the given points to solve for $a$ and $b$.

   Answer (b):

   $y = 0.25(6)^x$