Which characteristic equation has roots r=±3r = \pm 3r=±3?
r2−9=0r^2 - 9 = 0r2−9=0
r2+9=0r^2 + 9 = 0r2+9=0
r2−6r+9=0r^2 - 6r + 9 = 0r2−6r+9=0
r2−3r=0r^2 - 3r = 0r2−3r=0