What is the characteristic equation for an=4an−1−4an−2a_n = 4a_{n-1} - 4a_{n-2}an=4an−1−4an−2?
r2−4r+4=0r^2 - 4r + 4 = 0r2−4r+4=0
r2+4r+4=0r^2 + 4r + 4 = 0r2+4r+4=0
r2−4=0r^2 - 4 = 0r2−4=0
r2+4=0r^2 + 4 = 0r2+4=0