Evaluate Double integral over triangular region

In summary: So in summary, the double integral over the region 'd' of ye^x dA, where D is the triangular region with vertices (0,0), (2,4), and (6,0), can be evaluated by breaking it up into two integrals, using e^6-y = e^6e^-y and applying integration by parts. The limits of integration are 0 to 4 for y and 0.5y to 6-y for x.
  • #1
nlsherrill
323
1

Homework Statement


Evaluate the double integral.

[I don't know how to write it in latex, sorry, but its the double integral over the region 'd' of ye^x dA

D is the triangular region with vertices (0,0), (2,4), and (6,0).


Homework Equations





The Attempt at a Solution



So the limits of integration I have are .5y to 6-y with respect to x, and 0 to 4 with respect to y. I think this is right. The farthest I can get is:

Integral 0..4 ye^6-y - ye^.5y dy

I can't figure out how to integrate these terms. Any hints?
 
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  • #2
nlsherrill said:

Homework Statement


Evaluate the double integral.

[I don't know how to write it in latex, sorry, but its the double integral over the region 'd' of ye^x dA

D is the triangular region with vertices (0,0), (2,4), and (6,0).


Homework Equations





The Attempt at a Solution



So the limits of integration I have are .5y to 6-y with respect to x, and 0 to 4 with respect to y. I think this is right. The farthest I can get is:

Integral 0..4 ye^6-y - ye^.5y dy

I can't figure out how to integrate these terms. Any hints?
Here's your integral in LaTeX:
[tex]\int_{y = 0}^4 (ye^{6 - y} - ye^{y/2})dy[/tex]

Break this up into two integrals. Note that e6 - y = e6e-y

Integration by parts should work on both integrals.
 
  • #3
Thanks! forgot about integration by parts.
 

What is a double integral?

A double integral is a mathematical concept used to find the volume under a surface in three-dimensional space. It is similar to a regular integral, but instead of finding the area under a curve, it finds the volume under a surface.

What is a triangular region?

A triangular region is a two-dimensional shape that has three sides and three angles. It is called a triangular region because it is bounded by three lines that form a triangle.

How do you evaluate a double integral over a triangular region?

To evaluate a double integral over a triangular region, you first need to set up the limits of integration. This involves finding the equations of the three lines that bound the triangular region and setting them as the limits for the two integrals. Next, you need to convert the double integral into an iterated integral by integrating with respect to one variable first and then the other. Finally, you can solve the iterated integral to find the value of the double integral over the triangular region.

What is the purpose of evaluating a double integral over a triangular region?

Evaluating a double integral over a triangular region can help us find the volume under a surface in three-dimensional space. It is useful in various fields such as physics, engineering, and economics to calculate quantities such as mass, work, and profit.

What are some real-life applications of evaluating a double integral over a triangular region?

Some real-life applications of evaluating a double integral over a triangular region include calculating the center of mass of a three-dimensional object, finding the average value of a function over a three-dimensional region, and determining the total profit from a production process. It is also used in fluid mechanics to calculate the rate of fluid flow through a three-dimensional region.

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