Integration by parts I believe

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SUMMARY

The discussion focuses on solving the integral ∫x sin^2 x dx using integration by parts. The participants clarify the substitution of sin^2 x with the identity sin^2 x = (1 - cos(2x))/2, which simplifies the integral. The integration by parts formula ∫u dv = uv - ∫v du is applied correctly, with u = x and dv = (1 - cos(2x))/2. The final expression leads to a clearer path for solving the integral.

PREREQUISITES
  • Understanding of integration by parts
  • Familiarity with trigonometric identities, specifically sin^2 x = (1 - cos(2x))/2
  • Basic calculus skills, including differentiation and integration techniques
  • Knowledge of substitution methods in integration
NEXT STEPS
  • Study the application of integration by parts in various integral problems
  • Learn more about trigonometric identities and their applications in calculus
  • Explore advanced integration techniques, including substitution and partial fractions
  • Practice solving integrals involving products of polynomials and trigonometric functions
USEFUL FOR

Students studying calculus, particularly those focusing on integration techniques, as well as educators looking for examples of integration by parts and trigonometric substitutions.

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Homework Statement


∫x sin^2 x dx



Homework Equations



integration by parts ∫u dv= uv-∫ v du

The Attempt at a Solution


u=x dv=1-cos2x
v= 1/2 sin 2x
du=dx

is that correct

i substituted sin^2 x= 1-cos2x Am I allowed to do that.
 
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cos2x = 2cos^2x-1 = 1-2sin^2x=cos^2x-sin^2x

I believe you mean sin^2x = 1 - cos^2 x?
 
oh ok I understand.
 
So it would be ∫x (1-cos^2x) dx

and then i'd subsitute u= cos x
du=-sin x

so then it would be ∫x- u^2 x^2 dx

is that correct
 
You should use this identity \sin^2 x = \frac{1}{2}(1-\cos (2x)).
 

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