Integrate:-\ xcos 3 xdx




2 Answers

Anil Pannikar AskiitiansExpert-IITB
85 Points
12 years ago


Dear Aparna,


 cos(3x) = 4 cos3(x) - 3 cos(x)

substitute value of cos3(x) from above in the integral and solve by parts.

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Askiitians Expert

Anil Pannikar

IIT Bombay

vikas askiitian expert
509 Points
12 years ago

I = xcos3xdx

 integrating it by parts

 =x[cos3xdx] - {[cos3xdx]}dx

 now put cos3x = (cos3x+3cosx)/4   and integrate


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