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[2020-02-06 Thu 13:14]
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Session 49: Exchanging the Order of Integration | Part A: Double Integrals | 3. Double Integrals and Line Integrals in the Plane | Multivariable Calculus | Mathematics | MIT OpenCourseWare

1 Chalkboard

Figure 1: Exchanging order of integration

Figure 1: Exchanging order of integration

Figure 2: Example of exchanging order of integration

Figure 2: Example of exchanging order of integration

Figure 3: Example conclusion

Figure 3: Example conclusion

2 How can we exchanging the order of integration?

2.1 Front

How can we exchanging the order of integration?

Using these example: \({\displaystyle \int_0^2 \int_x^2 e^{-y^2} \dd{y}\dd{x}}\)

2.2 Back

  • Draw the graph of the boundaries, and detect the region
  • Calculate the inverse functions
  • Keep the function \(e^{-y^2}\), but on exchanging order these will be constants

\({\displaystyle \int_0^2 \int_0^y e^{-y^2} \dd{x} \dd{y}}\)

3 Why is it interesting to exchange the order of integration?

3.1 Front

Why is it interesting to exchange the order of integration?

Using these example: \({\displaystyle \int_0^2 \int_x^2 e^{-y^2} \dd{y}\dd{x}}\)

3.2 Back

Because \(e^{-y^2}\) has no simple antiderivative. Sometimes, iterated integrals are more complex in one way than in the other, so you can exchange order of integration