Q. 12

Question

Let ρ(x, y,z) be a density function defined on the rectangular solid R where R={(x,y,z)|a1xa2,b1yb2, and c1zc2}. Set up iterated integrals representing the mass of R, using all six distinct orders of integration.

Step-by-Step Solution

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Answer

The six distinct orders of integration representing the mass of R are,

a1a2b1b2c1c2 ρx,y,zdzdydxb1b2 a1a2c1c2ρx,y,zdzdxdy a1a2c1c2b1b2  ρx,y,zdydzdx c1c2a1a2 b1b2 ρx,y,zdydxdzb1b2c1c2a1a2ρx,y,zdxdzdyc1c2b1b2a1a2 ρx,y,zdxdydz

1Step 1 . Given information

R={(x,y,z)|a1xa2,b1yb2, and c1zc2}.

2Step 2 . The definition of the iterated triple integral:

If ρx,y,z be a density function defined on the rectangular solid R where R={(x,y,z)|axb,cyd, and ezf}then the mass of R is defined as, Ω ρx,y,zdV=abcdefρx,y,zdzdydx.

The other mass equations are defined in the same way for other 5 triple integrals. Given that ρx,y,z be a density function defined on the rectangular solid R where R={(x,y,z)|a1xa2,b1yb2, and c1zc2} then the mass of R is defined as Ωρx,y,zdV=a1a2b1b2c1c2 ρx,y,zdzdydx.

3Step 3 . The other five equations for the mass are,

b1b2 a1a2c1c2ρx,y,zdzdxdy a1a2c1c2b1b2  ρx,y,zdydzdx c1c2a1a2 b1b2 ρx,y,zdydxdzb1b2c1c2a1a2ρx,y,zdxdzdyc1c2b1b2a1a2 ρx,y,zdxdydz