Triple Integral 1E61B4
1. **State the problem:** We want to evaluate the triple integral $$\iiint_V \phi \, dV$$ where $$\phi = 4xz$$ and $$V$$ is the volume bounded by the planes $$2z + 4y + x = 2$$ and the coordinate planes $$x=0, y=0, z=0$$.
2. **Set up the region and limits:** The region $$V$$ is a tetrahedron in the first octant bounded by the coordinate planes and the plane $$2z + 4y + x = 2$$.
3. **Express the limits:**
- From the plane equation, solve for $$x$$: $$x = 2 - 4y - 2z$$.
- Since $$x, y, z \geq 0$$, the limits are:
- $$x$$ from $$0$$ to $$2 - 4y - 2z$$
- $$y$$ from $$0$$ to the value where $$x=0$$, so $$2 - 4y - 2z \geq 0 \Rightarrow 4y + 2z \leq 2$$
- $$z$$ from $$0$$ to the value where $$y=0$$, so $$2 - 2z \geq 0 \Rightarrow z \leq 1$$
4. **Find limits for $$y$$ and $$z$$:**
- For fixed $$z$$, $$y$$ ranges from $$0$$ to $$\frac{2 - 2z}{4} = \frac{1 - z}{2}$$.
- $$z$$ ranges from $$0$$ to $$1$$.
5. **Set up the integral:**
$$
\iiint_V 4xz \, dV = \int_0^1 \int_0^{\frac{1 - z}{2}} \int_0^{2 - 4y - 2z} 4xz \, dx \, dy \, dz
$$
6. **Integrate with respect to $$x$$:**
$$
\int_0^{2 - 4y - 2z} 4xz \, dx = 4z \int_0^{2 - 4y - 2z} x \, dx = 4z \left[ \frac{x^2}{2} \right]_0^{2 - 4y - 2z} = 2z (2 - 4y - 2z)^2
$$
7. **Substitute and integrate with respect to $$y$$:**
$$
\int_0^{\frac{1 - z}{2}} 2z (2 - 4y - 2z)^2 \, dy
$$
Let $$u = 2 - 4y - 2z$$, then $$du = -4 dy$$, so $$dy = -\frac{du}{4}$$.
When $$y=0$$, $$u = 2 - 0 - 2z = 2 - 2z$$.
When $$y = \frac{1 - z}{2}$$, $$u = 2 - 4 \cdot \frac{1 - z}{2} - 2z = 2 - 2(1 - z) - 2z = 2 - 2 + 2z - 2z = 0$$.
So the integral becomes:
$$
2z \int_{u=2 - 2z}^0 u^2 \left(-\frac{1}{4}\right) du = -\frac{z}{2} \int_{2 - 2z}^0 u^2 du = \frac{z}{2} \int_0^{2 - 2z} u^2 du
$$
Calculate the integral:
$$
\frac{z}{2} \left[ \frac{u^3}{3} \right]_0^{2 - 2z} = \frac{z}{2} \cdot \frac{(2 - 2z)^3}{3} = \frac{z (2 - 2z)^3}{6}
$$
8. **Integrate with respect to $$z$$:**
$$
\int_0^1 \frac{z (2 - 2z)^3}{6} dz = \frac{1}{6} \int_0^1 z (2 - 2z)^3 dz
$$
Let $$w = 2 - 2z$$, then $$dw = -2 dz$$, so $$dz = -\frac{dw}{2}$$.
When $$z=0$$, $$w=2$$.
When $$z=1$$, $$w=0$$.
Also, $$z = \frac{2 - w}{2}$$.
Rewrite the integral:
$$
\frac{1}{6} \int_{w=2}^0 \frac{2 - w}{2} w^3 \left(-\frac{1}{2}\right) dw = \frac{1}{6} \cdot \frac{1}{4} \int_0^2 (2 - w) w^3 dw = \frac{1}{24} \int_0^2 (2w^3 - w^4) dw
$$
9. **Calculate the integral:**
$$
\int_0^2 (2w^3 - w^4) dw = \left[ \frac{2 w^4}{4} - \frac{w^5}{5} \right]_0^2 = \left[ \frac{w^4}{2} - \frac{w^5}{5} \right]_0^2
$$
Evaluate at $$w=2$$:
$$
\frac{2^4}{2} - \frac{2^5}{5} = \frac{16}{2} - \frac{32}{5} = 8 - 6.4 = 1.6
$$
10. **Final value:**
$$
\frac{1}{24} \times 1.6 = \frac{1.6}{24} = 0.066666... \approx 0.07
$$
**Answer:** $$\boxed{0.07}$$ (rounded to 2 decimal places)