Which of these recurrence relations is non-homogeneous?
an=3an−1−2an−2a_n = 3a_{n-1} - 2a_{n-2}an=3an−1−2an−2
an=an−1+n2a_n = a_{n-1} + n^2an=an−1+n2
an=an−1+an−2a_n = a_{n-1} + a_{n-2}an=an−1+an−2
an=5an−1−6an−2a_n = 5a_{n-1} - 6a_{n-2}an=5an−1−6an−2