求微分方程y✀-ytanx=1∕cosx的通解

求详细过程
2025-04-01 23:31:08
推荐回答(1个)
回答1:

e^∫-tanxdx=e^∫-sinx/cosxdx=e^∫dcosx/cosx=e^lncosx=cosx
y'-ytanx=cosx
cosxy'-ytanxcosx=cos²x
cosxy'-ysinx=cos²x
(cosxy)`=cos²x
cosxy=∫cos²xdx+C
=1/2∫(1+cos2x)dx+C
=1/2(x+1/2∫cos2xd2x)+C
=1/2x+1/4∫cos2xd2x+C
=1/2x+1/4sin2x+C
y=(1/2x+1/4sin2x+C)/cosx