Which of the following is a non-homogeneous recurrence relation?
an=2an−1+an−2a_n = 2a_{n-1} + a_{n-2}an=2an−1+an−2
an=an−1+3a_n = a_{n-1} + 3an=an−1+3
an=an−1⋅an−2a_n = a_{n-1} \cdot a_{n-2}an=an−1⋅an−2
an=0a_n = 0an=0