Triple Integrals: Examples

1.Find the volume of the ellipsoidal solid given by MATH

Solution:

Because x,y, and z play similar roles in the equation, the order of integration is probably immaterial, and you arbitrarily choose

$dzdydx$. Moreover, you can simplify the calculation by considering only the portion of the ellipsoid lying in the first octant. From the order  $dzdydx$, you first determine the bounds for z:
MATH

Then, the boundaries for x any are:
MATH

Thus, you solve the following integral:
MATH

Use integration tables in the next step:
MATH
MATH




2. Evaluate MATH

Solution:

Note that after one integration in the given order, you would encounter the integral MATH which is not an elementary function. To avoid this problem, change the order of integration to $dzdxdy$, so that y is the outer variable. The solid region Q is given by:
MATH

From this we can notice that the projection of Q in the xy plane yields the bounds:
MATH

Therefore:
MATH
MATH

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