Trigonometric Subsitution Integral

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SUMMARY

The integral ∫cot²(x)csc⁴(x)dx can be solved using trigonometric substitution. The substitution u = cot(x) leads to the integral -∫u²(u² + 1)du, which expands to -∫(u⁴ + 2u³ + u²)du. The final result is -cot⁵(x)/5 - cot³(x)/3 + C. The discrepancy with Wolfram Alpha arises from the incorrect inclusion of the cot⁴(x)/2 term in the user's solution, which is not present in the correct answer.

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  • Understanding of trigonometric identities, specifically cotangent and cosecant functions.
  • Familiarity with integration techniques, particularly integration by substitution.
  • Knowledge of polynomial integration.
  • Experience with using computational tools like Wolfram Alpha for verification.
NEXT STEPS
  • Review trigonometric identities related to cotangent and cosecant functions.
  • Practice integration by substitution with various trigonometric functions.
  • Explore polynomial integration techniques to solidify understanding of integral calculus.
  • Learn how to verify integral solutions using computational tools like Wolfram Alpha.
USEFUL FOR

Students studying calculus, particularly those focusing on integral calculus and trigonometric integrals, as well as educators seeking to clarify common mistakes in solving such integrals.

Painguy
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Homework Statement


∫cot^2(x)csc^4(x)dx

Homework Equations


The Attempt at a Solution


∫cot^2(x)(cot^2(x)+1)csc^2(x)dx
u=cot(x)
du=-csc^2(x)dx
-∫u^2 (u^2 +1)du
-∫u^4 + 2u^3 + u^2 du
-(u^5)/5 - (u^4)/2 - (u^3)/3
-cot^5(x)/5 - cot^4(x)/2 - cot^3(x)/3 + C

Wolfram alpha shows the solution as -cot^5(x)/5 - cot^3(x)/3 + C

So I'm unsure as to how I got the cot^4(x)/2

What exactly did I do wrong or is wolfram wrong?

Thanks in advance
 
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Painguy said:

Homework Statement


∫cot^2(x)csc^4(x)dx



Homework Equations





The Attempt at a Solution


∫cot^2(x)(cot^2(x)+1)csc^2(x)dx
u=cot(x)
du=-csc^2(x)dx
-∫u^2 (u^2 +1)du
-∫u^4 + 2u^3 + u^2 du
-(u^5)/5 - (u^4)/2 - (u^3)/3
-cot^5(x)/5 - cot^4(x)/2 - cot^3(x)/3 + C

Wolfram alpha shows the solution as -cot^5(x)/5 - cot^3(x)/3 + C

So I'm unsure as to how I got the cot^4(x)/2

What exactly did I do wrong or is wolfram wrong?

Thanks in advance

Now how did you change u^2(u^2+1) into u^4 + 2u^3 + u^2?
 

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