We have, ‌x3−14x2+56x−64=0 ‌‌ at ‌x=2,8−14.4+56.2−64 ‌=8−56+112−64=0 Therefore, the given equation can be written as x2(x−2)−12x(x−2)+32(x−2)‌=0 (x−2)(x2−12x+32)‌=0 (x−2)(x−4)(x−8)‌=0 The roots are 2,4,8, which are in GP.