We can use a double Riemann sum to approximate the volume of a solid bounded above by a function of two variables over a rectangular region. By taking the limit, this becomes a double integral representing the volume of the solid.
Properties of double integral are useful to simplify computation and find bounds on their values.
We can use Fubini’s theorem to write and evaluate a double integral as an iterated integral.
Double integrals are used to calculate the area of a region, the volume under a surface, and the average value of a function of two variables over a rectangular region.
Key equations
Double integral
Iterated integral
or
Average value of a function of two variables
In the following exercises, use the midpoint rule with
and
to estimate the volume of the solid bounded by the surface
the vertical planes
and
and the horizontal plane
In the following exercises, estimate the volume of the solid under the surface
and above the rectangular region
R by using a Riemann sum with
and the sample points to be the lower left corners of the subrectangles of the partition.
The values of the function
f on the rectangle
are given in the following table. Estimate the double integral
by using a Riemann sum with
Select the sample points to be the upper right corners of the subsquares of
R .