Question

请问这个积分怎么求，谢谢

Answer 1

积分=8/T^2∫(T/2,0)tcos(nwt)dt
=8/(nwT^2)∫(T/2,0)tcos(nwt)d(nwt)
=8/(nwT^2)∫(T/2,0)tdsin(nwt)
=8/(nwT^2)tsin(nwt)(T/2,0)-8/(nwT^2)∫(T/2,0)sin(nwt)dt
=8/(nwT^2)tsin(nwt)(T/2,0)-8/(n^2w^2T^2)∫(T/2,0)sin(nwt)d(nwt)
=8/(nwT^2)tsin(nwt)(T/2,0)+8/(n^2w^2T^2)∫(T/2,0)dcos(nwt)
=8/(nwT^2)tsin(nwt)(T/2,0)+8/(n^2w^2T^2)cos(nwt)(T/2,0）
=4/(nwT)sin(nwT/2)+8/(n^2w^2T^2)cos(nwT/2)-8/(n^2w^2T^2).

Answer 2

积分=8/T^2∫(T/2,0)tcos(nwt)dt
=8/(nwT^2)∫(T/2,0)tcos(nwt)d(nwt)
=8/(nwT^2)∫(T/2,0)tdsin(nwt)
=8/(nwT^2)tsin(nwt)(T/2,0)-8/(nwT^2)∫(T/2,0)sin(nwt)dt
=8/(nwT^2)tsin(nwt)(T/2,0)-8/(n^2w^2T^2)∫(T/2,0)sin(nwt)d(nwt)
=8/(nwT^2)tsin(nwt)(T/2,0)+8/(n^2w^2T^2)∫(T/2,0)dcos(nwt)
=8/(nwT^2)tsin(nwt)(T/2,0)+8/(n^2w^2T^2)cos(nwt)(T/2,0）
=4/(nwT)sin(nwT/2)+8/(n^2w^2T^2)cos(nwT/2)-8/(n^2w^2T^2).
望采纳~~