Which of the following equations is a linear recurrence?
an=an−1+an−2a_n = a_{n-1} + \sqrt{a_{n-2}}an=an−1+an−2
an=an−1⋅na_n = a_{n-1} \cdot nan=an−1⋅n
an=3an−1+2an−2a_n = 3a_{n-1} + 2a_{n-2}an=3an−1+2an−2
an=(an−1)2a_n = (a_{n-1})^2an=(an−1)2