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Please help integrate -4sin(mx)^3dx Please! Thanks!?
Please integrate -4sin(mx)^3 dx
The problem is in the trigonometric substitution section so you will have to use it somewhere probably.
Thanks for your help!
1 Answer
- HemantLv 71 decade agoFavorite Answer
I = ∫ ( - 4 sin³ mx ) dx ...... (1)
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We have
sin ( 3 mx ) = 3 sin mx - 4 sin³ mx
so that
- 4 sin³ mx = sin (3mx) - 3 sin mx.
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Hence, from (1),
I = ∫ [ sin (3mx) - 3 sin (mx) ] dx
..= [ - ( cos 3mx ) / (3m) ] - 3 [ - ( cos mx ) / (m) ] + C
..= ( - 1/ 3m) cos 3mx + ( 3/m ) cos mx + C ...................... Ans.
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Happy To Help !
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