EUROPEAN JOURNAL OF PURE AND APPLIED MATHEMATICS Vol. 17, No. 4, 2024, 3622-3641 ISSN 1307-5543 – ejpam.com Published by New York Business Global A Novel Analytical Approximate Solution for Strongly Nonlinear Third-Order Jerk Equations Using a Modified Iteration Method Gamal M. Ismail1,2,∗, Mohammed I. Yamani1 1 Department of Mathematics, Faculty of Science, Islamic University of Madinah, Madinah, 42351, Saudi Arabia 2 Department of Mathematics, Faculty of Science, Sohag University, Sohag 82524, Egypt Abstract. Nonlinear jerk equations, characterized by a third-order time derivative, play a crucial role in modeling various physical phenomena across disciplines like mechanics, circuits, and biol- ogy. Accurately solving these equations is essential for understanding and predicting the behavior of such systems. However, obtaining analytical solutions for nonlinear jerk equations can be chal- lenging, necessitating the development of robust and accurate approximation methods. This work explores, for the first time, the application of the modified iteration approach to solve third-order jerk equations. By comparing the obtained approximate solutions with both exact and existing an- alytical solutions for established engineering problems, we demonstrate the superior accuracy and rapid convergence of the proposed method. The significantly reduced error percentages highlight the effectiveness of the modified iteration approach in providing precise solutions for nonlinear jerk equations, paving the way for its application in a wide range of oscillation problems within nonlinear sciences and engineering. 2020 Mathematics Subject Classifications: 34A34, 34C15, 34C25, 35L65, 37N30 Key Words and Phrases: Modified iteration method, Third-order jerk equations, Analytical solutions, Nonlinear oscillator, Exact solution 1. Introduction Differential equations are widely employed to describe the evolution of complex systems in many fields, including physics and engineering. Nonlinear differential equations play a crucial role in modeling various scientific phenomena and have many applications in various branches of science. Researchers seek effective solutions to such problems using analytical or numerical approaches. Recently, there has been an increasing interest in analytical solutions for nonlinear differential equations. The key issue in studying nonlinear differential equations is finding ∗Corresponding author. DOI: https://doi.org/10.29020/nybg.ejpam.v17i4.5427 Email addresses: gamalm2010@yahoo.com (G. M. Ismail), shingl6600@gmail.com (M. I. Yamani) https://www.ejpam.com 3622 Copyright: © 2024 The Author(s). (CC BY-NC 4.0) G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3623 the exact solutions. On the other hand, computing the exact results can be challenging, es- pecially in equations with a high degree of nonlinearity, mainly using traditional analytical techniques. To overcome this problem, many novel approaches are presented to deal with this shortage. For example, harmonic balance method [1–3], variational iteration method [4, 5], Hamiltonian approach [6, 7], modified algebraic method [8, 9], global residue har- monic balance method [10, 11], energy balance method [12–14]. linearizing method [15], multiple scales method [16], non-perturbative approach [17, 18], Adomian decomposition method [19], optimal variational iteration method [20] and Galerkin method [21]. These analytical approaches have been extensively utilized to examine the frequency and periodic solutions of nonlinear oscillators. Nonlinear third-order Jerk equations are useful for analyzing structures with rotating and translating movements, such as machine tools or robots [22]. Nonlinear third-order jerk equations are differential equations that describe the evolution of a system’s jerk, which is the rate of change of acceleration. In simpler terms, it represents the ”snap” or ”jolt” felt when acceleration changes abruptly. Jerk equations are powerful tools for modeling complex dynamical systems exhibiting rich and often unpredictable behavior. Understanding their properties and developing effective methods for their analysis is cru- cial for advancing our knowledge in various scientific and engineering disciplines. Nonlinear third-order Jerk equations may explain a variety of physical issues, includ- ing third-order mechanical oscillators [23]. Nowadays, due to the need of knowing the analytical solutions of the nonlinear Jerk equations. Several diverse techniques have been proposed to find the analytical solutions of like these problems such as block method [24], harmonic balance method [25, 26], homotopy perturbation method [27], parameter perturbation method [28], Mickens iteration method [29], Linstedt-Poincare methods [30], residue harmonic balance method [31], multiple scales Lindstedt-Poincare method [32], differential transform method [33], modified harmonic balance method [34], variational iteration method [35] and homotopy asymptotic method [36] to solve the present prob- lems. Recently, Ismail and Abu-Zinadah [37] used the global error minimization method for solving the current problems. In this study, we apply the modified iteration technique, a powerful analytical method with high accuracy and efficiency, to obtain higher-order analytic approximations for non- linear Jerk equations. The primary advantage of this method lies in its ability to provide both simplicity and accuracy when solving higher-order differential equations. The nu- merical solution is obtained using the fourth-order Runge-Kutta method. A comparison between the analytical and numerical solutions, presented through tables and correspond- ing figures, emphasizes the accuracy of the modified iteration technique. 2. The iteration procedure Consider a non-linear equation ẍ+ f(x, ẋ, ẍ) = 0, x(0) = A, ẋ(0) = 0. (1) G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3624 Rewrite Eq. (1) to be in the form: ẍ+ ω2x = ω2x− f(x, ẋ, ẍ) ≊ F (xk, ẋk, ẍk), (2) where ẋ and ẍ represent the first and second derivatives with respect to time, respectively, and ω is an unknown constant. According to Ref [38], Eq. (2) can be rewritten as ẍk+1 + ω2 kxk+1 = F (xk, ẋk, ẍk) , k = 0, 1, 2, ..., (3) and the imputes of starting functions are x0(t) = A cosω0t. (4) It is further required that for each k, the solution to Eq. (3), is to satisfy initial conditions xk+1(0) = A, ẋk+1(0) = 0. (5) 3. Applications In this section, we illustrate the fundamental concept of the modified iteration approach by considering the following non-linear differential equation: ... x + f (x, ẋ, ẍ) , x(0) = 0, ẋ(0) = A, ẍ(0) = 0. (6) Following [3], the general non-linear third order Jerk equation has the form ... x = −γ ẋ− αẋ3 − βx2ẋ+ δxẋẍ− εẋ ẍ2, (7) with x(0) = 0, ẋ(0) = A, ẍ(0) = 0. (8) where the parameters α, β, γ, δ and ε are constants. 3.1. Jerk function containing time’s velocity times acceleration and ve- locity In this case at γ = δ = 1, α = β = ε = 0, in Eq. (7), the non-linear equation is in the following [1]: ... x + ẋ− xẋẍ = 0, x(0) = 0, ẋ(0) = A, ẍ(0) = 0. (9) Eq. (9) can be rewritten in the form ẋ = y, ẏ = ẍ, (10) G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3625 then Eq. (10) becomes ÿ + y − ȳyẏ = 0, y(0) = A, ẏ(0) = 0. (11) where ȳ is the integration of x ÿ + ω2y = ω2y − y + ȳyẏ. (12) The iteration technique according to Eq. (3) is ÿk+1 + ω2 kyk+1 = ω2 kyk − yk + ȳkykẏk. (13) 3.1.1. First iteration solution For the first iteration, at k = 0, we get ÿ1 + ω2 0y1 = ω2 0y0 − y0 + ȳ0y0ẏ0. (14) According to Eq. (4), we have y0(t) = A cosω0t. (15) Inserting Eq. (15) into Eq. (14), to obtain ÿ1 + ω2 0y1 = 1 4 ( −4A−A3 + 4Aω2 0 ) cos(ω0t)− A3 4 cos(3ω0t). (16) A secular term is a term in the solution that grows linearly or polynomially with time. Secular terms often arise when using naive perturbation methods on systems with natural frequencies that are close to being resonant with the perturbation frequency. Secular terms are undesirable for several reasons, for example, breakdown of perturbation theory and loss of periodicity: To avoid secular term from equation (16), we obtain ω0 = 1 2 √ 4 +A2. (17) Solving Eq. (16) with initial conditions (5), the first approximate solution y1 of is obtained as y1 = ( A+ A3 32ω2 0 ) cos(ω1t)− A3 32ω2 0 cos(3ω1t). (18) 3.1.2. Second iteration solution For the second level of iteration continuing to k = 1. Substituting Eq. (18) into Eq. (13), to obtain ÿ2 + ω2 1y2 = − ( A(32+9A2)(6144+4608A2+1136A4+93A6−384(4+A2)2ω2 1 3072(4+A2)3 ) cos(ω1t) + ( A3(9216+7936A2+2296A4+223A6−64(4+A2)2ω2 1) 512(4+A2)3 ) cos(3ω1t) + ( A5(3328+1928A2+279A4) 1536(4+A2)3 ) cos(5ω1t) + ( 13A7(32+9A2) 6144(4+A2)3 ) cos(7ω1t) − ( A9 2048(4+A2)3 ) cos(9ω1t). . (19) G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3626 To avoid dominating terms, we obtain ω1 = √ 6144 + 4608A2 + 1136A4 + 93A6 6144 + 3072A2 + 384A4 . (20) After solving Eq. (19) with the initial conditions, we have the second approximate solution. y2 = ( A3(103680+85120A2+23485A4+2178A6)+720A(4+A2)2(256+63A2)ω2 1 46080(4+A2)33ω2 1 ) cos(ω2t) + ( A3(103680+85120A2+23485A4+2178A6)+720A(4+A2)2(256+63A2)ω2 1 4096(4+A2)3ω2 1 ) cos(3ω2t) + ( A5(3328+1928A2+279A4) 36864(4+A2)3ω2 1 ) cos(5ω2t) + ( 13A7(32+9A2) 294912(4+A2)3ω2 1 ) cos(7ω2t) + ( A9 163840(4+A2)3ω2 1 ) cos(9ω2t). (21) 3.1.3. Third iteration solution For the third level of iteration, continuing to k = 2, we substituting y2 from Eq. (21) into the right-hand side of Eq. (13), we have. ÿ3 + ω2 2y3 = ω2 2y2 − y2 + ȳ2y2ẏ2. (22) Solving Equation (22), and avoiding secular terms, we can obtain ω2 by using Mathematica command software program. The findings found for y3, need too much space and cannot be shown here. However, the numerical values will be shown in the findings and discussion part. ω2 = ( √ (1/(4 +A2)9A(1470839609502185029632000 + 4826192468679044628480000A2 +7296583778952951103488000A4 + 6729655286686996758528000A6 +4224062453812034745139200A8 + 1905190794429295126118400A10 +635148579378340823040000A12 + 158430275820381536256000A14 +29559820082388423147520A16 + 4072969446127757557760A18 +402650199557972162560A20 + 27028701991773424000A22 +1103351520402981540A24 + 20664999056050911A26))) /(3840 √ 7 √ ( 1 (4+A2)7 A(6144 + 4608A2 + 1136A4 + 93A6)2(23592960 +24330240A2 + 9397760A4 + 1618520A6 + 105309A8))). (23) Integrating Eq. (21), we obtain the analytical solution of Eq. (9) in the form: x = (( 4A(23592960+24330240A2+9397760A4+1618520A6+105309A8) ω2 ) sin(ω2t) − ( 20A3(49152+43008A2+12640A4+1245A6) ω2 ) sin(3ω2t) + ( 26624A5+15424A7+2232A9 ω2 ) sin(5ω2t)− ( 2080A7+585A9 7ω2 ) sin(7ω2t) + ( A9 ω2 ) sin(9ω2t) ) / ( 3840(4 +A2)(6144 + 4608A2 + 1136A4 + 93A6) ) (24) G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3627 3.2. Jerk function containing velocity times acceleration-squared, and ve- locity Another case of the Jerk equation is considered by putting γ = ε = 1 , α = β = δ = 0, in Eq. (7) to obtain [1]: ... x + ẋ+ ẋẍ2 = 0, x(0) = 0, ẋ(0) = A, ẍ(0) = 0. (25) Similar to application (1), Eq. (25) can be rewritten in the form ÿ + y + yẏ2 = 0 y(0) = A, ẏ(0) = 0. (26) Following the iteration scheme (3), we have ÿk+1 + ω2 k+1yk+1 = ω2 kyk − yk − ykẏ 2 k. (27) 3.2.1. First iteration solution For first iteration at k = 0, we get ÿ1 + ω2 0y1 = 1 4 ( −4ẏ + 4ẏω2 0 −A3ω2 0 ) cos(ω0t) + A3ω2 0 4 cos(3ω0t). (28) To avoid secular term from equation (28), we obtain ω0 = 2√ 4−A2 . (29) Solving Eq. (28) with initial conditions (5), the first approximate solution y1 is obtained as y1 = ( A+ A3 32 ) cos(ω1t)− A3 32 cos(3ω1t). (30) 3.2.2. Second iteration solution For the second level of iteration continuing to k = 1 gives, ÿ2 + ω2 1y2 = ( −A(32+A2)(2048+(−2048+512A2−48A4+7A6)ω2 1) 65536 ) cos(ω1t) + ( A3(1024+(7168+1280A2+56A4+3A6)ω2 1) 32768 ) cos(3ω1t) −. ( A5(1792+88A2+A4)ω2 1 32768 ) cos(5ω1t) + ( 15A7(32+A2)ω2 1 131072 ) cos(7ω1t) − ( 9A9ω2 1) 131072 ) cos(9ω1t). . (31) To avoid dominating terms in Eq (31), we obtain ω1 = 32 √ 2 √ 32 +A2 √ 65536− 14336A2 + 1024A4 − 176A6 − 7A8 , (32) G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3628 After solving Eq. (31) with the initial conditions, we have the second approximate solution. y2 = ( A+ 7A3 256 + A5 384 + 35A7 196608 + 23A9 1966080 + A3 256ω2 1 ) cos(ω2t) − ( A3(1024+(7168+1280A2+56A4+3A6)ω2 1) 262144ω2 1 ) cos(3ω2t) + ( A5(1792+88A2+A4) 786432 ) cos(5ω2t)− ( 5A7(32+A2) 2097152 ) cos(7ω2t) + ( 9A9 10485760 ) cos(9ω2t). (33) 3.2.3. Third iteration solution For the third level of iteration continuing to k = 2. Substituting y2 from Eq. (32) into the right hand side of Eq. (13), we have ÿ3 + ω2 2y3 = ω2 2y2 − y2 − y2ẏ 2 2. (34) Solving Eq. (34), and avoiding secular terms, we can obtain ω2 in the same manner as application (1). The numerical data will be presented in the findings and discussion section. ω2 = ( 10485760 √ 23592960A+737280A3+38400A5+6360A7−39A9 2048−512A2+48A4−7A6 ) /(√ ((−2594073385365405696000A+ 567453553048682496000A3 −44754521296994304000A5 − 3232564185661440000A7 +172513374398054400A9 + 248228493865779200A11 +19274524734259200A13 + 2109308770713600A15 +185788373401600A17 + 8293138432000A19 + 200006092800A21 +2252995200A23 + 174151100A25 − 997773A27)/(−2048 + 512A2 −48A4 + 7A6))) . (35) Integrating Eq. (33), we obtain the analytical solution of Eq. (25) in the form: x = 1 220200960 ω2 ( −28A ( −7864320− 245760A2 − 12800A4 − 2120A6 + 13A8 ) sin(ω2t) +140A3 ( −16384− 2048A2 − 160A4 +A6 ) sin(3ω2t) +(100352A5 + 4928A7 + 56A9) sin(5ω2t) − (2400A7 + 75A9) sin(7ω2t) + 21A9 sin(9ω2t) ) . . (36) 4. Discussions In this section, the approximate analytical solutions of Eqs. (9) and (25), obtained using the modified iteration approach as shown in Eqs. (24) and (36), are compared with those obtained from fourth-order Runge-Kutta numerical solutions and other known analytical methods from the literature. This comparison is presented in Figures 1 − 4 G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3629 and Tables 1− 6. The graphical representations clearly demonstrate that the results ob- tained from the present approach are in excellent agreement with those obtained using the fourth-order Runge-Kutta method. Moreover, the present approach accurately predicts the periodic behavior of the equations over a wide range. To demonstrate the exceptional accuracy of the modified iteration technique, we ex- amine two cases of non-linear third-order jerk equations. We compare the approximate results obtained using this technique with existing analytical solutions from the literature and with numerical integration results to validate the accuracy of the solutions derived. For the same cases discussed using the block method [24], harmonic balance method [25], homotopy perturbation method [27], Linstedt-Poincare methods [30], residue har- monic balance method [31], multiple scales Lindstedt-Poincare [32], modified harmonic balance method [34], differential transform method [33], and global error minimization method [37], the present results were compared with those obtained by the modified itera- tion technique, as shown in Tables 1− 6. The numerical results show excellent agreement with the third-order approximate analytical solutions obtained in this study using the modified iteration technique. A comparison between the higher-order approximate solution, the differential trans- form method [33], and the modified global error minimization method [37] with the cor- responding numerical solution is presented in Figures 1 − 4 for A = 0.3 and A = 1. It is clear that the approximation of the solution using the modified iteration technique agrees with the differential transform method, the modified global error minimization method, and the numerical solution. Furthermore, the approximate frequencies agree well with the corresponding exact solutions, implying that using the modified iteration technique with higher orders produces realistic results. We looked at the percentage error (%) by the definition to confirm the accuracy. Error = ∣∣∣∣Te − TApp Te ∣∣∣∣× 100%. where the various approximate periods obtained by TApp and Te represents the correspond- ing exact period of the oscillator. G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3630 Table 1: Comparison of the approximate and exact solutions for Eq. (9). A Te T3current T3 [37] T3 [32] T3 [31] T3 [27] T3 [30] T3 [25] T3 [34] 0.1 6.275347 6.275347 6.275347 6.2753468 6.275346837 6.27534684 6.275348 6.275346 6.275346837 0 0 3.19e −6 2.59e −6 2.55e −6 1.59e −5 1.59e −5 2.59e −6 0.2 6.252016 6.252016 6.252016 6.2520158 6.25201599 6.25201599 6.252028 6.252003 6.25201599 0 0 3.19e −6 1.59e −7 1.59e −7 1.92e −4 2.08e −4 1.59e −7 0.5 6.096061 6.096061 6.096061 6.0960246 6.09606050 6.09605904 6.096491 6.095585 6.096060516 0 0 5.97e −4 8.20e −6 3.12e −5 0.00706 0.00781 7.93e −7 1 5.626007 5.62587 5.62602 5.6245487 5.62599289 5.62579479 5.630343 5.619852 5.62599937 2.43e −5 2.31e −4 0.02592 2.51e −4 0.00377 0.07707 0.10940 1.36e −4 2 4.491214 4.48492 4.47661 4.4664554 4.49012538 4.48208113 4.509311 4.442883 4.49112308 0.14014 0.47234 0.55127 0.02424 0.20335 0.40294 1.07612 0.00202 Table 2: Comparison between the numerical solution and analytical solutions at A = 0.2 for Eq. (9) t Block Method MDTM [4/4] and Present Solution Numerical Solution [24] [5/5] [33] 0 0 0 0 0 0.125 0.024934 0.024951214 0.024934943 0.024935034 0.25 0.049480 0.049511005 0.049480664 0.049480891 0.375 0.073253 0.073293861 0.073253553 0.073253560 0.5 0.095881 0.095926024 0.095881202 0.095881465 0.625 0.117008 0.117051228 0.117007962 0.117008021 0.75 0.1363 0.136336241 0.136300404 0.136300551 0.875 0.153453 0.153476143 0.153452636 0.153452785 1 0.168191 0.168199251 0.168191377 0.168191348 1.125 0.180281 0.180271603 0.180280677 0.180280833 1.25 0.180281 0.180271603 0.180280677 0.180280833 1.375 0.195778 0.195739784 0.195778569 0.195778587 1.5 0.198937 0.198888450 0.198936744 0.198936684 1.625 0.198949 0.198896377 0.198949462 0.198949302 1.75 0.195816 0.195763266 0.195816515 0.195816396 1.875 0.189589 0.189539059 0.189588706 0.189588464 2 0.180367 0.180323081 0.180366838 0.180366565 G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3631 Table 3: Comparison between the numerical solution and analytical solutions at A = 0.4 for Eq. (9) t Block Method MDTM [4/4] and Present Solution Numerical Solution [24] [5/5] [33] 0 0 0 0 0 0.125 0.049869 0.049869861 0.049869861 0.049870029 0.25 0.098960 0.098960562 0.098960558 0.098961002 0.375 0.146501 0.146501385 0.146501379 0.146501402 0.5 0.191739 0.191738916 0.191738937 0.191739420 0.625 0.233947 0.233946661 0.233946816 0.233946758 0.75 0.272436 0.272435646 0.272436179 0.272435964 0.875 0.306566 0.306566039 0.306567314 0.306566352 1 0.33576 0.335759596 0.335761911 0.335759593 1.125 0.359513 0.359512477 0.359515583 0.359513002 1.25 0.377408 0.377407791 0.377410047 0.377407810 1.375 0.389127 0.389126999 0.389124206 0.389127373 1.5 0.39446 0.394459308 0.394443406 0.394459515 1.625 0.393308 0.393308207 0.393266152 0.393308138 1.75 0.385695 0.385694562 0.385607769 0.385694560 1.875 0.371756 0.371755941 0.371755564 0.371600658 2 0.351742 0.351742248 0.351491092 0.351741644 G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3632 Figure 1: Comparison between higher order analytical solution (black line), MGEMM [37] (red line), and the numerical solution (blue line) at A = 1, for Eq. (9). G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3633 Figure 2: Comparison between higher order analytical solution (black line), MDTM [33] (red line), and the numerical solution (blue line) at A = 0.3, for Eq. (9). G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3634 Table 4: Comparison of the approximate and exact solutions for Eq. (25). A Te T3current T3 [37] T3 [32] T3 [31] T3 [27] T3 [30] T3 [25] T3 [34] 0.1 6.27533378 6.27533378 6.27533378 6.27533378 6.2753338 6.27533378 6.275329 6.2753264 6.27533378 0 0 0 0 0 7.61e −5 1.18e −4 0 0.2 6.251809 6.25180898 6.25180898 6.25180884 6.25180911 6.25182078 6.251740 6.251690 6.2518089 3.19e −7 3.19e −7 2.56e −6 1.76e −6 1.88e −4 0.00110 0.00190 1.59e −6 0.5 6.088449 6.08845097 6.08845017 6.08841902 6.08848374 6.08815979 6.085649 6.083668 6.088450 3.24e −5 1.92e −5 4.92e −4 5.71e −4 0.00475 0.04599 0.07853 1.64e −5 1 5.527200 5.527510790 5.527656919 5.52576588 5.52994105 5.50818960 5.477174 5.441398 5.527497 0.00562 0.00827 2.59e −4 0.04959 0.343943 0.90509 1.55236 0.00537 2 4.690247 4.6831871 4.7771790 4.68572454 4.72603111 4.44735707 4.412733 4.155936 4.683269 0.15052 1.85346 0.09642 0.76295 5.17847 5.91683 11.39196 0.14878 Table 5: Comparison between the numerical solution and analytical solutions at A = 0.2 for Eq. (25) t Block Method MDTM [4/4] and Present Solution Numerical Solution [24] [5/5] [33] 0 0 0 0 0 0.125 0.024934 0.024934942 0.024934943 0.024935034 0.25 0.049480 0.049480663 0.049480664 0.049480891 0.375 0.073253 0.073253551 0.073253552 0.073253560 0.5 0.095881 0.095881197 0.095881199 0.095881461 0.625 0.117008 0.117007942 0.117007949 0.117008005 0.75 0.1363 0.136300334 0.136300356 0.136300499 0.875 0.153452 0.153452432 0.153452503 0.153452647 1 0.168191 0.168190868 0.168191071 0.168191036 1.125 0.18028 0.180279542 0.180280059 0.180280209 1.25 0.189525 0.189523851 0.189525026 0.189524937 1.375 0.195777 0.195774284 0.195776702 0.195776711 1.5 0.198934 0.198929290 0.198933855 0.198933786 1.625 0.198945 0.198937278 0.198945268 0.198945100 1.75 0.195811 0.195797675 0.195810754 0.195810626 1.875 0.189581 0.189560997 0.189581165 0.189580915 2 0.180357 0.180327919 0.180357378 0.180357098 G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3635 Table 6: Comparison between the numerical solution and analytical solutions at A = 0.4 for Eq. (25) t Block Method MDTM [4/4] and Present Solution Numerical Solution [24] [5/5] [33] 0 0 0 0 0 0.125 0.049869 0.049869861 0.049869863 0.049870029 0.25 0.098960 0.098960556 0.098960576 0.098961001 0.375 0.146501 0.146501354 0.146501423 0.146501386 0.5 0.191739 0.191738758 0.191738937 0.191739302 0.625 0.233946 0.233945991 0.233946416 0.233946249 0.75 0.272434 0.272433351 0.272434399 0.272434276 0.875 0.306562 0.306559422 0.306562164 0.306561832 1 0.335749 0.335743004 0.33575013 0.335749291 1.125 0.359492 0.359475362 0.359492741 0.359492282 1.25 0.37737 0.377332285 0.377371297 0.377370224 1.375 0.389065 0.388985315 0.389065644 0.389064877 1.5 0.394363 0.394211444 0.394363972 0.394363009 1.625 0.393169 0.392900613 0.393169669 0.393168420 1.75 0.385503 0.385060429 0.385504547 0.385503391 1.875 0.371507 0.370817684 0.371508112 0.371506638 2 0.351432 0.350416451 0.351432939 0.351431339 G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3636 Figure 3: Comparison between higher order analytical solution (black line), MGEMM [37] (red line), and the numerical solution (blue line) at A = 1, for Eq. (25). G. M. Ismail, M. I. Yamani / Eur. J. Pure Appl. Math, 17 (4) (2024), 3622-3641 3637 Figure 4: Comparison between higher order analytical solution (black line), MDTM [33] (red line), and the numerical solution (blue line) at A = 0.3, for Eq. (25). REFERENCES 3638 5. Conclusion In this study, a modified iteration approach was developed and employed to solve two nonlinear third-order jerk equations with broad engineering applications. The modified approach successfully determined approximate analytical solutions for these equations. A comparison of the obtained results with numerical solutions demonstrated the excellent accuracy of the proposed method. The present approach offers solutions in a readily usable analytical form, exhibiting superior accuracy and a wider range of applicability compared to other established analytical methods found in the literature. This technique proves to be a powerful and effective mathematical tool for solving highly nonlinear third-order dif- ferential equations arising in mathematical physics, applied mathematics, and engineering. Furthermore, the iterative nature of the method allows for the computation of higher-order approximations to achieve even greater accuracy if desired. The modified iteration tech- nique facilitates the straightforward calculation of these higher-order terms, leading to solutions that closely approximate the exact solutions. Consequently, the present method demonstrates consistent and reliable performance, offering a simple yet effective approach for obtaining novel solutions to a variety of nonlinear problems. 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