What is the characteristic equation for an=2an−1−an−2a_n = 2a_{n-1} - a_{n-2}an=2an−1−an−2?
r=2r = 2r=2
(r−1)2=0(r-1)^2 = 0(r−1)2=0
r2−2r+1=0r^2 - 2r + 1 = 0r2−2r+1=0
Both a and b