Instability of a Nonlinear Differential Equation of Fifth Order with Variable Delay Year: 2012 Volume: 6 Issue: 8 1012 - 1014 Pages Authors: Cemil Tunc Abstract: In this paper, we study the instability of the zero solution to a nonlinear differential equation with variable delay. By using the Lyapunov functional approach, some sufficient conditions for instability of the zero solution are obtained. Keywords: Instability Lyapunov-Krasovskii functional delay differential equation fifth order.