Problem 2: (25%) Solve from 0 to 3 with h = 0.1 by writing MATLAB codes, and display all your results on the same graph. dy -ysin' y(0)-1 dt 1) Heun's method without corrector, 2) Ralston's method. Problem 3: (25%) Given the initial conditions, y(0) = 1 and y'(0) = 0, solve the following initial-value problem from 0 to 4 by writing MATLAB codes with a step size of 0.125. d² y +4y=0 di" 1) Euler's method; 2) Fourth-order RK method (Bonus problem, 10%); 3) Plot both solutions on the same graph along with the exact solution y = cos 2t.