Integral Evaluation F30395
1. **Problem Statement:** Evaluate the definite integral $$\int_0^1 \frac{x e^x}{(x+1)^2} \, dx$$.
2. **Method:** Use substitution to simplify the integral. Let $$u = x + 1$$, so $$x = u - 1$$ and $$dx = du$$.
3. **Change limits:** When $$x=0$$, $$u=1$$; when $$x=1$$, $$u=2$$.
4. **Rewrite the integral:**
$$\int_0^1 \frac{x e^x}{(x+1)^2} \, dx = \int_1^2 \frac{(u-1) e^{u-1}}{u^2} \, du$$.
5. **Simplify the integrand:**
$$= \int_1^2 \frac{(u-1)}{u^2} e^{u-1} \, du = \int_1^2 \left(\frac{u}{u^2} - \frac{1}{u^2}\right) e^{u-1} \, du = \int_1^2 \left(\frac{1}{u} - \frac{1}{u^2}\right) e^{u-1} \, du$$.
6. **Rewrite as:**
$$\int_1^2 \frac{e^{u-1}}{u} \, du - \int_1^2 \frac{e^{u-1}}{u^2} \, du$$.
7. **Use integration by parts on the second integral:**
Let $$I = \int_1^2 \frac{e^{u-1}}{u} \, du$$ and $$J = \int_1^2 \frac{e^{u-1}}{u^2} \, du$$.
8. For $$J$$, set $$v = e^{u-1}$$ and $$w = -\frac{1}{u}$$, then
$$J = \int e^{u-1} u^{-2} du = -\frac{e^{u-1}}{u} \Big|_1^2 + \int_1^2 \frac{e^{u-1}}{u} du = -\frac{e^{1}}{2} + \frac{e^{0}}{1} + I = -\frac{e}{2} + 1 + I$$.
9. Substitute back into the original integral:
$$I - J = I - \left(-\frac{e}{2} + 1 + I\right) = I - (-\frac{e}{2} + 1 + I) = \frac{e}{2} - 1$$.
10. **Final answer:**
$$\int_0^1 \frac{x e^x}{(x+1)^2} \, dx = \frac{e}{2} - 1$$.