Double Integral Region E7790F
1. **Problem statement:** Evaluate the double integral $$\iint_R (x+1) \, dA$$ where $R$ is the region bounded by $y=1$ and $y=x^2$ for $x$ in $[-2,2]$.
2. **Set up the integral:** The region $R$ lies between the curves $y=x^2$ (lower curve) and $y=1$ (upper curve). For each fixed $x$ in $[-2,2]$, $y$ ranges from $x^2$ to $1$. So the integral becomes:
$$\int_{-2}^2 \int_{x^2}^1 (x+1) \, dy \, dx$$
3. **Integrate with respect to $y$ first:** Since $x+1$ does not depend on $y$, the inner integral is:
$$\int_{x^2}^1 (x+1) \, dy = (x+1)(1 - x^2)$$
4. **Rewrite the integral:** Now the integral reduces to:
$$\int_{-2}^2 (x+1)(1 - x^2) \, dx$$
5. **Expand the integrand:**
$$(x+1)(1 - x^2) = (x+1) - (x+1)x^2 = x + 1 - x^3 - x^2$$
6. **Simplify the integrand:**
$$x + 1 - x^3 - x^2 = -x^3 - x^2 + x + 1$$
7. **Integrate term-by-term:**
$$\int_{-2}^2 (-x^3 - x^2 + x + 1) \, dx = \int_{-2}^2 -x^3 \, dx - \int_{-2}^2 x^2 \, dx + \int_{-2}^2 x \, dx + \int_{-2}^2 1 \, dx$$
8. **Evaluate each integral:**
- $$\int_{-2}^2 -x^3 \, dx = 0$$ (odd function over symmetric interval)
- $$\int_{-2}^2 x^2 \, dx = \left[ \frac{x^3}{3} \right]_{-2}^2 = \frac{8}{3} - \left(-\frac{8}{3}\right) = \frac{16}{3}$$
- $$\int_{-2}^2 x \, dx = 0$$ (odd function over symmetric interval)
- $$\int_{-2}^2 1 \, dx = 2 - (-2) = 4$$
9. **Combine results:**
$$0 - \frac{16}{3} + 0 + 4 = 4 - \frac{16}{3} = \frac{12}{3} - \frac{16}{3} = -\frac{4}{3}$$
**Final answer:**
$$\boxed{-\frac{4}{3}}$$