Determine the stability of the recurrence an=0.9an−1+0.05an−2a_n = 0.9a_{n-1} + 0.05a_{n-2}an=0.9an−1+0.05an−2.
Stable, because both roots have absolute value less than 1.
Unstable, because one root is greater than 1.
Marginally stable, because one root is exactly 1.
Unstable, because the sum of coefficients is less than 1.