Integral Expansion 40Cb15
1. **State the problem:** We need to evaluate the integral $$\int (\sqrt{x} + 1)(x - \sqrt{x} + 1) \, dx$$.
2. **Expand the integrand:** Multiply the two binomials:
$$ (\sqrt{x} + 1)(x - \sqrt{x} + 1) = \sqrt{x} \cdot x + \sqrt{x} \cdot (-\sqrt{x}) + \sqrt{x} \cdot 1 + 1 \cdot x + 1 \cdot (-\sqrt{x}) + 1 \cdot 1 $$
3. **Simplify each term:**
- $\sqrt{x} \cdot x = x^{3/2}$
- $\sqrt{x} \cdot (-\sqrt{x}) = -x$
- $\sqrt{x} \cdot 1 = \sqrt{x}$
- $1 \cdot x = x$
- $1 \cdot (-\sqrt{x}) = -\sqrt{x}$
- $1 \cdot 1 = 1$
4. **Combine like terms:**
$$ x^{3/2} - x + \sqrt{x} + x - \sqrt{x} + 1 = x^{3/2} + 1 $$
5. **Rewrite the integral:**
$$ \int (x^{3/2} + 1) \, dx $$
6. **Integrate term-by-term:**
- Integral of $x^{3/2}$ is $$ \frac{x^{5/2}}{\frac{5}{2}} = \frac{2}{5} x^{5/2} $$
- Integral of $1$ is $x$
7. **Write the final answer:**
$$ \int (\sqrt{x} + 1)(x - \sqrt{x} + 1) \, dx = \frac{2}{5} x^{5/2} + x + C $$
where $C$ is the constant of integration.