Please prove using induction

We can consider the number f(n) of perfect matchings in a 3 2n grid graph, which is the same as the number of ways to tile a 3 2n rectangle with 1 2 dominoes. (a) Prove that f(0) = 1, f(1) = 3, and that for positive n, f(n) = 3f(n 1) + 2f(n 2) + ... + 2f(0)