Which of these is a linear homogeneous recurrence?
an=3an−1+4an−2a_n = 3a_{n-1} + 4a_{n-2}an=3an−1+4an−2
an=an−12a_n = a_{n-1}^2an=an−12
an=an−1+1a_n = a_{n-1} + 1an=an−1+1
an=nan−1a_n = n a_{n-1}an=nan−1