Consider the sequence defined by an=2an−1+an−2−2an−3a_n = 2a_{n-1} + a_{n-2} - 2a_{n-3}an=2an−1+an−2−2an−3. What is the characteristic equation?
r3−2r2−r+2=0r^3 - 2r^2 - r + 2 = 0r3−2r2−r+2=0
r3+2r2+r−2=0r^3 + 2r^2 + r - 2 = 0r3+2r2+r−2=0
r3−r2−2r+2=0r^3 - r^2 - 2r + 2 = 0r3−r2−2r+2=0
2r3−r2−r+1=02r^3 - r^2 - r + 1 = 02r3−r2−r+1=0