# Trying to understand the iterative method for solving recurrences in this example [duplicate]

This question: Solving the recurrence T(n) = 3T(n-2) with iterative method has a pretty straightforward step-by-step for solving this particular recurrence. But, I'm having trouble understanding two things.

1) How dos OP arrive at this general form? If we know T(n)=3T(n−2) and T(n−2)=3T(n−4), then my substitution gives:

T(n)=3T*3T(n−4)


Why is it not 3T*3T, or 3T^2? Is it some specific behavior of T that determines this?

T(n)=3∗3T(n−4)