Consider an=2an−1−2an−2a_n = 2a_{n-1} - 2a_{n-2}an=2an−1−2an−2. What are the roots of the characteristic equation?
1±i1 \pm i1±i
2±i2 \pm i2±i
1±2i1 \pm 2i1±2i
±2i\pm \sqrt{2}i±2i