Find the solution to the following Ihcc recurrence:
$a_n = 9a_{n-2}$ for $n \ge 2$ with initial conditions $a_0 = 3$, $a_1 = 0$. The solution is of the form:
$a_n = \alpha_1(r_1)^n + \alpha_2(r_2)^n$
for suitable constants $\alpha_1, \alpha_2, r_1, r_2$ with $r_1 \le r_2$. Find these constants.
$r_1 = $
$r_2 = $
$\alpha_1 = $
$\alpha_2 = $
