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bii17
 3 years ago
integrate (x)(cos^3 x) dx
bii17
 3 years ago
integrate (x)(cos^3 x) dx

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sirm3d
 3 years ago
Best ResponseYou've already chosen the best response.0do you know the reduction formula for \[\int \cos^n x \,\mathrm dx\]

matricked
 3 years ago
Best ResponseYou've already chosen the best response.1first simplify cos^3 x in terms of cosine of 3x and x and then integrate by parts

matricked
 3 years ago
Best ResponseYou've already chosen the best response.1i don't think here u should use reduction formula

bii17
 3 years ago
Best ResponseYou've already chosen the best response.0its \[\cos ^3 x\] .. where did u get 3x and x @matricked

matricked
 3 years ago
Best ResponseYou've already chosen the best response.1use cos3x =4 cos^3 (x)  3cos x

sirm3d
 3 years ago
Best ResponseYou've already chosen the best response.0why not? it solves the problem too, but the solution may not be attractive to @bii17

matricked
 3 years ago
Best ResponseYou've already chosen the best response.1i mean use cos^3 (x) =1/4 *(cos3x +3cosx)

bii17
 3 years ago
Best ResponseYou've already chosen the best response.0oh okay.. then what will happen next ? @matricked

matricked
 3 years ago
Best ResponseYou've already chosen the best response.1and then use by parts

bii17
 3 years ago
Best ResponseYou've already chosen the best response.0\[1/4 [x(\cos 3x + 3\cos x)]dx\] is this correct? @matricked

bii17
 3 years ago
Best ResponseYou've already chosen the best response.0so there will be u and du den dv and v... i used Dv as cos 3x dx the V will be 1/3 sin 3x ???

matricked
 3 years ago
Best ResponseYou've already chosen the best response.1for both integration of 1/4 *xcos3x take x as the first function

bii17
 3 years ago
Best ResponseYou've already chosen the best response.0i get it.. thanks a lot :) @matricked
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