Math Problem Statement

Rewrite the following integral using the indicated order of integration and then evaluate the resulting integral.

Integral from 0 to 5 Integral from negative 1 to 0 Integral from 0 to 6 x plus 6 dy dx dz∫05∫−10∫06x+6 dy dx dz

in the order dz dx dy

Solution

To rewrite and evaluate the integral in the order dzdxdydz \, dx \, dy, let’s first analyze the bounds given for the original order dydxdzdy \, dx \, dz.

Step 1: Rewrite in terms of dzdxdydz \, dx \, dy

The original integral is:

051006x+6dydxdz\int_0^5 \int_{-1}^0 \int_0^{6x + 6} \, dy \, dx \, dz

Looking at the inner integral 06x+6dy\int_0^{6x + 6} \, dy, we see that this limits yy from 00 to 6x+66x + 6.

Now, let’s change the order to dzdxdydz \, dx \, dy. We need to determine the limits for zz, xx, and yy based on this new order:

  1. Outer integral in yy: From the original limits of xx (from 1-1 to 00), we can express yy bounds as they affect xx:

    • yy is bounded by 0y60 \leq y \leq 6 (since yy can reach a maximum of 66 when x=0x = 0).
  2. Middle integral in xx: For each fixed yy, xx is bounded by the range where y6x+6y \leq 6x + 6, solving:

    • xx is bounded by 1xy61-1 \leq x \leq \frac{y}{6} - 1.
  3. Inner integral in zz: zz remains bounded from 00 to 55 in all cases.

Thus, rewriting the integral in the order dzdxdydz \, dx \, dy, we have:

061y6105dzdxdy\int_0^6 \int_{-1}^{\frac{y}{6} - 1} \int_0^5 \, dz \, dx \, dy

Step 2: Evaluate the resulting integral

Now, we evaluate each integral step-by-step:

  1. Integrate with respect to zz:

    061y6105dzdxdy=061y61[z]05dxdy\int_0^6 \int_{-1}^{\frac{y}{6} - 1} \int_0^5 \, dz \, dx \, dy = \int_0^6 \int_{-1}^{\frac{y}{6} - 1} \left[ z \right]_0^5 \, dx \, dy

    =061y615dxdy= \int_0^6 \int_{-1}^{\frac{y}{6} - 1} 5 \, dx \, dy

  2. Integrate with respect to xx:

    =06[5x]1y61dy= \int_0^6 \left[ 5x \right]_{-1}^{\frac{y}{6} - 1} \, dy

    =06(5(y61)5(1))dy= \int_0^6 \left( 5 \left( \frac{y}{6} - 1 \right) - 5(-1) \right) \, dy

    =06(5y65+5)dy= \int_0^6 \left( \frac{5y}{6} - 5 + 5 \right) \, dy

    =065y6dy= \int_0^6 \frac{5y}{6} \, dy

  3. Integrate with respect to yy:

    =5606ydy= \frac{5}{6} \int_0^6 y \, dy

    =56y2206= \frac{5}{6} \cdot \frac{y^2}{2} \Big|_0^6

    =56362=5618=15= \frac{5}{6} \cdot \frac{36}{2} = \frac{5}{6} \cdot 18 = 15

Final Answer:

051006x+6dydxdz=15\int_0^5 \int_{-1}^0 \int_0^{6x + 6} \, dy \, dx \, dz = 15

Would you like further clarification or steps on this process?

Here are some related questions:

  1. How do you determine the limits of integration when changing the order?
  2. What are common methods to simplify nested integrals?
  3. How does the geometry of the region affect the integration limits?
  4. What is the importance of checking boundaries in multivariable integrals?
  5. How can double integrals simplify solving triple integrals in some cases?

Tip: Carefully analyze the bounds of each variable when changing the order of integration; sketching the region can help visualize limits.

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Math Problem Analysis

Mathematical Concepts

Multivariable Calculus
Triple Integrals
Changing Order of Integration

Formulas

Triple Integral Formula: ∫∫∫ f(x, y, z) dz dx dy
Basic Integration: ∫ a dx = ax + C

Theorems

Fubini's Theorem

Suitable Grade Level

Undergraduate Level