“…one part of this important equations is multi-order differential equations. Many researchers have studied this kind of differential equations by using different ways and methods, such as: generalized sine-cosine wavelets [13], Boubaker polynomials [1], homotopy analysis method [3], Legendre pseudo-spectral method [14], Chebyshev operational matrix method [4], and wavelet collocation method [5], Other related studies are on: modified HPM for solving generalized linear complex differential equations [9], solving fractional differential equations using Haar wavelet techniques [11], studies on the mathematical model of HIV infection of CD + 4 T by using HPM and VIM [2], studies of general second-order partial differential equations using HPM [6], of general first-order partial differential equations using HPM [7], and solving generalized Riccati differential equation [8]. One of the most popular methods for solving equations is variational iteration (VIM), and in the present work we use this method for solving a class of multi-order ordinary differential equation.…”