3. A higher-order differential equation is given below:
d^3y/dt^3 + 2 d^2y/dt^2 - dy/dt - 2y = e^t (0 < t < 1.5)
with the initial conditions y(0) = 0, y(0)' = 1, and y(0)'' = 2.
(a) Reduce the above governing equation to an equivalent system, in the form of a set of first-order ordinary differential equations.
(b) For an initial-value problem y' = f(x,y) with initial condition y(x0) = y0, the Modified Euler method is written as yn+1 = yn + 0.5Δh(y'n + y'*n+1), with the initial guess y'*n+1 = f(xn+1, y*n+1) and y*n+1 = yn + Δh y'n. Using the Modified Euler method with a step size of 0.6, determine the numerical solution of the above initial-value problem (a).
(c) To solve the differential equation dy/dx = f(x,y) with initial condition y(x0) = y0, the second-order Runge-Kutta approximation is written as
yn+1 = yn + aΔhf(xn, yn) + bΔhf(xn + cΔh, yn + dΔhf(xn, yn)).
By specifying a = b = 0.5, c = d = 1, and using a step size of 0.6, determine the numerical solution of the above initial-value problem (a).