Calculus 3 change of variables

In summary, the conversation discusses using the change of variables method to evaluate a given integral over a region enclosed by four boundary lines. The suggestion is to first draw the region in both the xy and uv planes to determine the bounds, and then use the standard change of variables approach. The person expresses difficulty with drawing the boundary lines but is reminded of the importance of accurately drawing them in order to solve the problem effectively.
  • #1
princessp
4
0

Homework Statement


Use the change of variables to evaluate the integral
(x +y ) sin(x -y )dA, where R is the
region enclosed by y = x, y = x - 2, y = -x and y = -x + 1. (Hint: use u = x + y and
v = x - y

Homework Equations

The Attempt at a Solution


Not sure how to start it
 
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  • #2
Draw the region in the xy plane and then draw the region in the uv plane to determine bounds. From there, use the standard change of variables...
 
  • #3
okay i think that's where i am having trouble. I an not good at drawing the graph
 
  • #4
princessp said:
okay i think that's where i am having trouble. I an not good at drawing the graph

You have to draw the boundary lines. Don't say that you can not draw the lines y = x, y = x - 2, y = -x, and y = -x + 1 !
 

What is "Calculus 3 change of variables"?

"Calculus 3 change of variables" refers to the process of transforming an integral from one set of variables to another, in order to make it easier to evaluate. This technique is commonly used in multivariable calculus to solve complex integrals.

Why is change of variables useful in calculus?

Change of variables allows us to simplify integrals by transforming them into a different coordinate system where the integrand may have a simpler form. This can make it easier to evaluate integrals and solve problems in calculus.

What are some common substitution strategies used in change of variables?

Some common substitution strategies used in change of variables include polar coordinates, spherical coordinates, cylindrical coordinates, and trigonometric substitutions. These strategies are used to transform the variables in an integral into a more manageable form.

How do you determine the appropriate change of variables for an integral?

To determine the appropriate change of variables for an integral, you should first identify the type of integral you are working with (e.g. double, triple), and then consider which substitution strategy would be most effective based on the variables involved. It may also be helpful to graph the region of integration and visualize the transformation.

What are some applications of change of variables in real-world problems?

Change of variables has many applications in real-world problems, such as in physics, engineering, and economics. For example, it can be used to calculate the mass of an object with non-uniform density, or to determine the optimal path for a particle moving through a 3D space. It is also commonly used in statistics and probability to transform data into a more manageable form for analysis.

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