1. **Problem statement:** Evaluate the integral $$\int \frac{2 + x}{(1 + x)^2} \, dx$$.
2. **Formula and approach:** We can split the integral into simpler parts or use substitution. Here, letโs split the numerator:
$$\int \frac{2 + x}{(1 + x)^2} \, dx = \int \frac{2}{(1 + x)^2} \, dx + \int \frac{x}{(1 + x)^2} \, dx$$.
3. **Evaluate the first integral:**
Use substitution $u = 1 + x$, so $du = dx$.
$$\int \frac{2}{u^2} \, du = 2 \int u^{-2} \, du = 2 \left(-u^{-1}\right) + C = -\frac{2}{1 + x} + C$$.
4. **Evaluate the second integral:**
Rewrite $x = u - 1$, so
$$\int \frac{x}{(1 + x)^2} \, dx = \int \frac{u - 1}{u^2} \, du = \int \left(\frac{u}{u^2} - \frac{1}{u^2}\right) du = \int \left(u^{-1} - u^{-2}\right) du$$.
5. **Integrate term by term:**
$$\int u^{-1} \, du = \ln|u| + C$$
$$\int u^{-2} \, du = -u^{-1} + C$$
So,
$$\int \left(u^{-1} - u^{-2}\right) du = \ln|u| + \frac{1}{u} + C = \ln|1 + x| + \frac{1}{1 + x} + C$$.
6. **Combine results:**
$$\int \frac{2 + x}{(1 + x)^2} \, dx = -\frac{2}{1 + x} + \ln|1 + x| + \frac{1}{1 + x} + C = \ln|1 + x| - \frac{1}{1 + x} + C$$.
---
1. **Problem statement:** Evaluate the integral $$\int \frac{2x^2}{1 - x^2} \, dx$$.
2. **Rewrite the integrand:**
Note that $1 - x^2 = (1 - x)(1 + x)$, but better to use polynomial division since degree numerator $=2$ and denominator $=2$.
3. **Divide numerator by denominator:**
$$\frac{2x^2}{1 - x^2} = \frac{2x^2}{1 - x^2} = \frac{2x^2}{-(x^2 - 1)} = -\frac{2x^2}{x^2 - 1}$$.
Divide $2x^2$ by $x^2 - 1$:
$$2x^2 \div (x^2 - 1) = 2 + \frac{2}{x^2 - 1}$$.
So,
$$-\frac{2x^2}{x^2 - 1} = -(2 + \frac{2}{x^2 - 1}) = -2 - \frac{2}{x^2 - 1}$$.
4. **Rewrite integral:**
$$\int \frac{2x^2}{1 - x^2} \, dx = \int \left(-2 - \frac{2}{x^2 - 1}\right) dx = -2 \int dx - 2 \int \frac{1}{x^2 - 1} dx$$.
5. **Integrate first term:**
$$-2 \int dx = -2x + C$$.
6. **Integrate second term:**
Use partial fractions:
$$\frac{1}{x^2 - 1} = \frac{1}{(x - 1)(x + 1)} = \frac{A}{x - 1} + \frac{B}{x + 1}$$.
Solve for $A$ and $B$:
$$1 = A(x + 1) + B(x - 1)$$.
Set $x=1$: $$1 = A(2) + B(0) \Rightarrow A = \frac{1}{2}$$.
Set $x=-1$: $$1 = A(0) + B(-2) \Rightarrow B = -\frac{1}{2}$$.
So,
$$\int \frac{1}{x^2 - 1} dx = \int \left(\frac{1/2}{x - 1} - \frac{1/2}{x + 1}\right) dx = \frac{1}{2} \ln|x - 1| - \frac{1}{2} \ln|x + 1| + C$$.
7. **Combine logarithms:**
$$\frac{1}{2} \ln \left|\frac{x - 1}{x + 1}\right| + C$$.
8. **Final answer:**
$$\int \frac{2x^2}{1 - x^2} dx = -2x - 2 \cdot \frac{1}{2} \ln \left|\frac{x - 1}{x + 1}\right| + C = -2x - \ln \left|\frac{x - 1}{x + 1}\right| + C$$.
Integral Evaluation Fcb6Eb
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.