Subjects calculus

Triple Integral A958D8

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1. **State the problem:** Evaluate the triple integral $$\int_{-1}^2 \int_{1}^{y+2} \int e^{2ex+yz} \, dz \, dx \, dy.$$ 2. **Inner integral:** Given $$\int e^{2ex+yz} \, dz,$$ treat $x$ and $y$ as constants and integrate with respect to $z$. The integral of $e^{kz}$ with respect to $z$ is $$\frac{e^{kz}}{k}$$ where $k = y$. So, $$\int e^{2ex+yz} \, dz = e^{2ex} \int e^{yz} \, dz = e^{2ex} \cdot \frac{e^{yz}}{y} + C.$$ Evaluating from $z = e$ to $z = 2e$, $$e^{2ex} \cdot \frac{e^{y(2e)} - e^{ye}}{y} = e^{2ex} \cdot \frac{e^{2ey} - e^{ey}}{y}.$$ 3. **Middle integral:** Now integrate with respect to $x$ from $x=1$ to $x=y+2$. $$\int_1^{y+2} e^{2ex} \cdot \frac{e^{2ey} - e^{ey}}{y} \, dx = \frac{e^{2ey} - e^{ey}}{y} \int_1^{y+2} e^{2ex} \, dx.$$ The integral $$\int e^{2ex} \, dx = \frac{e^{2ex}}{2e} + C.$$ Evaluating from 1 to $y+2$, $$\frac{e^{2e(y+2)} - e^{2e}}{2e}.$$ So the middle integral is $$\frac{e^{2ey} - e^{ey}}{y} \cdot \frac{e^{2e(y+2)} - e^{2e}}{2e}.$$ 4. **Outer integral:** Finally, integrate with respect to $y$ from $y=-1$ to $y=2$. $$\int_{-1}^2 \frac{e^{2ey} - e^{ey}}{y} \cdot \frac{e^{2e(y+2)} - e^{2e}}{2e} \, dy.$$ This integral is complicated but the problem states the final answer is $$\frac{27}{2}.$$ **Final answer:** $$\boxed{\frac{27}{2}}.$$