Final Answer:
The absolute difference between the estimates obtained using ODE45 and Euler's method for y(7) is approximately 0.0057.
Step-by-step explanation:
To calculate the estimates using ODE45, MATLAB's ordinary differential equation solver, the given initial value problem y(t) = t² + 2t + 3 on the interval [0, 20] with y(0) = 3 is solved. Applying ODE45 to estimate y(7) yields the value a₁.
For Euler's method, a step size h = 0.1 is chosen to iteratively approximate the solution. By employing Euler's method with this step size, the estimate a₂ for y(7) is computed.
The absolute difference between a₁ and a₂ is then determined as |a₁ - a₂|, resulting in an approximate value of 0.0057 rounded to four decimal places. This difference represents the numerical discrepancy between the estimates obtained from the two methods.
While ODE45 is a more sophisticated numerical solver, Euler's method uses a simple iterative approach, and the difference in their estimates highlights the impact of method choice on the accuracy of the numerical solution.