1. **State the problem:**
We want to evaluate the surface integral $$\iint_S \mathbf{F} \cdot d\mathbf{S}$$ where $$\mathbf{F}(x,y,z) = (2x^2 + e^y)\mathbf{i} + 5xy\mathbf{j} + 8z\mathbf{k}$$ and $$S$$ is the surface bounding the region $$E$$ defined by the coordinate planes $$x=0, y=0, z=0$$, the planes $$x=3, y=2$$, and the plane $$x+z=4$$.
2. **Use the Divergence Theorem:**
The Divergence Theorem states:
$$\iint_S \mathbf{F} \cdot d\mathbf{S} = \iiint_E \nabla \cdot \mathbf{F} \, dV$$
where $$\nabla \cdot \mathbf{F}$$ is the divergence of $$\mathbf{F}$$.
3. **Calculate the divergence:**
$$\nabla \cdot \mathbf{F} = \frac{\partial}{\partial x}(2x^2 + e^y) + \frac{\partial}{\partial y}(5xy) + \frac{\partial}{\partial z}(8z)$$
Calculate each partial derivative:
- $$\frac{\partial}{\partial x}(2x^2 + e^y) = 4x$$ (since $$e^y$$ is constant w.r.t. $$x$$)
- $$\frac{\partial}{\partial y}(5xy) = 5x$$
- $$\frac{\partial}{\partial z}(8z) = 8$$
So,
$$\nabla \cdot \mathbf{F} = 4x + 5x + 8 = 9x + 8$$
4. **Set up the volume integral:**
The region $$E$$ is bounded by:
- $$0 \leq x \leq 3$$
- $$0 \leq y \leq 2$$
- $$0 \leq z \leq 4 - x$$ (from $$x + z = 4$$)
The volume integral is:
$$\iiint_E (9x + 8) \, dV = \int_0^3 \int_0^2 \int_0^{4-x} (9x + 8) \, dz \, dy \, dx$$
5. **Integrate with respect to $$z$$:**
$$\int_0^{4-x} (9x + 8) \, dz = (9x + 8) \times (4 - x) = (9x + 8)(4 - x)$$
6. **Simplify the integrand:**
$$ (9x + 8)(4 - x) = 36x + 32 - 9x^2 - 8x = -9x^2 + 28x + 32 $$
7. **Integrate with respect to $$y$$:**
Since the integrand does not depend on $$y$$,
$$\int_0^2 (-9x^2 + 28x + 32) \, dy = 2(-9x^2 + 28x + 32) = -18x^2 + 56x + 64$$
8. **Integrate with respect to $$x$$:**
$$\int_0^3 (-18x^2 + 56x + 64) \, dx = \left[-6x^3 + 28x^2 + 64x\right]_0^3$$
Calculate each term at $$x=3$$:
- $$-6(3)^3 = -6 \times 27 = -162$$
- $$28(3)^2 = 28 \times 9 = 252$$
- $$64(3) = 192$$
Sum:
$$-162 + 252 + 192 = 282$$
At $$x=0$$, the expression is 0.
9. **Final answer:**
$$\iint_S \mathbf{F} \cdot d\mathbf{S} = 282$$
Divergence Theorem 78D5A8
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