1. **State the problem:** Solve the differential equation $$y' + \frac{2y - 1}{x} = x + 1$$.
2. **Rewrite the equation:** Distribute the fraction:
$$y' + \frac{2y}{x} - \frac{1}{x} = x + 1$$
Rearranged:
$$y' + \frac{2}{x}y = x + 1 + \frac{1}{x}$$
3. **Identify the type:** This is a linear first-order differential equation of the form
$$y' + P(x)y = Q(x)$$
where $$P(x) = \frac{2}{x}$$ and $$Q(x) = x + 1 + \frac{1}{x}$$.
4. **Find the integrating factor (IF):**
$$\mu(x) = e^{\int P(x) dx} = e^{\int \frac{2}{x} dx} = e^{2 \ln|x|} = x^2$$
5. **Multiply both sides by the integrating factor:**
$$x^2 y' + x^2 \cdot \frac{2}{x} y = x^2 \left(x + 1 + \frac{1}{x}\right)$$
Simplify:
$$x^2 y' + 2x y = x^3 + x^2 + x$$
6. **Recognize the left side as a derivative:**
$$\frac{d}{dx} (x^2 y) = x^3 + x^2 + x$$
7. **Integrate both sides:**
$$x^2 y = \int (x^3 + x^2 + x) dx + C$$
Calculate the integral:
$$\int x^3 dx = \frac{x^4}{4}, \quad \int x^2 dx = \frac{x^3}{3}, \quad \int x dx = \frac{x^2}{2}$$
So,
$$x^2 y = \frac{x^4}{4} + \frac{x^3}{3} + \frac{x^2}{2} + C$$
8. **Solve for $$y$$:**
$$y = \frac{1}{x^2} \left( \frac{x^4}{4} + \frac{x^3}{3} + \frac{x^2}{2} + C \right) = \frac{x^2}{4} + \frac{x}{3} + \frac{1}{2} + \frac{C}{x^2}$$
**Final answer:**
$$y = \frac{x^2}{4} + \frac{x}{3} + \frac{1}{2} + \frac{C}{x^2}$$
Linear Differential 5Ed91E
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