What is the characteristic equation of an=an−1+6an−2a_n = a_{n-1} + 6a_{n-2}an=an−1+6an−2?
r2−r−6=0r^2 - r - 6 = 0r2−r−6=0
r2+r−6=0r^2 + r - 6 = 0r2+r−6=0
r2−r+6=0r^2 - r + 6 = 0r2−r+6=0
r2+r+6=0r^2 + r + 6 = 0r2+r+6=0