Euler Method 4Ef712
1. **State the problem:** We want to approximate the solution to the differential equation $$y' = x + y$$ with initial condition $$y(0) = 0$$ using Euler's method with step size $$h = 0.2$$ for 6 steps.
2. **Recall Euler's method formula:**
$$y_{n+1} = y_n + h f(x_n, y_n)$$
where $$f(x,y) = x + y$$ is the derivative function.
3. **Initialize:**
$$x_0 = 0, y_0 = 0$$
4. **Calculate each step:**
- Step 1: $$x_1 = x_0 + h = 0 + 0.2 = 0.2$$
$$y_1 = y_0 + h (x_0 + y_0) = 0 + 0.2 (0 + 0) = 0$$
- Step 2: $$x_2 = 0.4$$
$$y_2 = y_1 + 0.2 (x_1 + y_1) = 0 + 0.2 (0.2 + 0) = 0.04$$
- Step 3: $$x_3 = 0.6$$
$$y_3 = y_2 + 0.2 (x_2 + y_2) = 0.04 + 0.2 (0.4 + 0.04) = 0.04 + 0.2 (0.44) = 0.04 + 0.088 = 0.128$$
- Step 4: $$x_4 = 0.8$$
$$y_4 = y_3 + 0.2 (x_3 + y_3) = 0.128 + 0.2 (0.6 + 0.128) = 0.128 + 0.2 (0.728) = 0.128 + 0.1456 = 0.2736$$
- Step 5: $$x_5 = 1.0$$
$$y_5 = y_4 + 0.2 (x_4 + y_4) = 0.2736 + 0.2 (0.8 + 0.2736) = 0.2736 + 0.2 (1.0736) = 0.2736 + 0.21472 = 0.48832$$
- Step 6: $$x_6 = 1.2$$
$$y_6 = y_5 + 0.2 (x_5 + y_5) = 0.48832 + 0.2 (1.0 + 0.48832) = 0.48832 + 0.2 (1.48832) = 0.48832 + 0.297664 = 0.785984$$
5. **Final approximate values:**
$$y(0.2) \approx 0$$
$$y(0.4) \approx 0.04$$
$$y(0.6) \approx 0.128$$
$$y(0.8) \approx 0.2736$$
$$y(1.0) \approx 0.48832$$
$$y(1.2) \approx 0.785984$$
This completes 6 steps of Euler's method with step size 0.2.