Solve the system of recurrences: an=an−1+bn−1a_n = a_{n-1} + b_{n-1}an=an−1+bn−1 and bn=2an−1b_n = 2a_{n-1}bn=2an−1. What is ana_nan in terms of an−1a_{n-1}an−1 and an−2a_{n-2}an−2?
an=2an−1+an−2a_n = 2a_{n-1} + a_{n-2}an=2an−1+an−2
an=an−1+an−2a_n = a_{n-1} + a_{n-2}an=an−1+an−2
an=an−1+2an−2a_n = a_{n-1} + 2a_{n-2}an=an−1+2an−2
an=3an−1−an−2a_n = 3a_{n-1} - a_{n-2}an=3an−1−an−2