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1-pi-0-2pi-xcos-nx-dx-Help-




Question Number 192687 by Mastermind last updated on 24/May/23
(1/π)∫_0 ^(2π) xcos(nx)dx    Help!
1π02πxcos(nx)dxHelp!
Answered by Subhi last updated on 24/May/23
  x=u     ⇛   du = dx  cos(nx)dx = dv  v=(1/n)∫n.cos(nx) = (1/n).sin(nx)  ∫u.dv = u.v−∫v.du  = x.((sin(nx))/n)−(1/n)∫sin(nx).dx  x.((sin(nx))/n)+(1/n^2 )∫−n.sin(nx).dx  x.((sin(nx))/n)+(1/n^2 ).cos(nx)+c  (1/π)∫x.cos(nx)dx = x.((sin(nx))/(nπ))+(1/(n^2 .π))cos(nx)+c
x=udu=dxcos(nx)dx=dvv=1nn.cos(nx)=1n.sin(nx)u.dv=u.vv.du=x.sin(nx)n1nsin(nx).dxx.sin(nx)n+1n2n.sin(nx).dxx.sin(nx)n+1n2.cos(nx)+c1πx.cos(nx)dx=x.sin(nx)nπ+1n2.πcos(nx)+c
Commented by Subhi last updated on 24/May/23
to find the definite integral, it will differ if (n) is integer or fraction
tofindthedefiniteintegral,itwilldifferif(n)isintegerorfraction

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