Double integration using trig term

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SUMMARY

The discussion centers on the double integral \int^1_0 \int^1_y sin(x^2) dx dy and the challenges faced in integrating it. The user initially attempts to reverse the order of integration to \int^1_0 \int^1_x sin(x^2) dy dx, but encounters difficulties. A correction is suggested, leading to the proper bounds of \int^1_0 \int^x_0, which simplifies the integral to \int^1_0 x sin(x^2) dx. The final evaluation yields -1/2 cos (x^2) | 1_0, confirming the solution.

PREREQUISITES
  • Understanding of double integrals
  • Familiarity with trigonometric functions, specifically sin(x^2)
  • Knowledge of integration techniques, including reversing the order of integration
  • Ability to visualize regions defined by integral limits
NEXT STEPS
  • Study the properties of double integrals in calculus
  • Learn techniques for changing the order of integration in multiple integrals
  • Explore integration by substitution methods for trigonometric functions
  • Practice visualizing regions of integration with graphical representations
USEFUL FOR

Students studying calculus, particularly those focusing on double integrals and integration techniques, as well as educators looking for examples of common pitfalls in integration problems.

glog
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Homework Statement



\int^1_0 \int^1_y sin(x^2) dx dy

The Attempt at a Solution



This equation cannot be integrated nicely, so I tried to reverse the order of integration:

\int^1_0 \int^1_x sin(x^2) dy dx

However this only helps for the first step, since when we intregrate by y, we get:

\int^1_0 sin(x^2)-xsin(x^2) dx

I'm stuck... again! Any ideas?
 
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glog said:
This equation cannot be integrated nicely, so I tried to reverse the order of integration:
\int^1_0 \int^1_x sin(x^2) dy dx
Your limits in the new double integral is incorrect. If in doubt, look at the original double integral and draw a picture of the region enclosed by the limits. Then try to express the limits of the double integral in the reversed order of the same region.
 
Alright so perhaps the bounds are then: \int^1_0 \int^x_0

In which case, my integral simplifies to:

\int^1_0 x sin(x^2)

Which becomes:

-1/2 cos (x^2) | 1_0

This make sense?
 
Yep, you got it.
 

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