4、=∫ 1/3*lnxd(x^3) = 1/3*lnx*x^3 -∫ 1/3*x^2 dx = 1/3*lnx*x^3 - 1/9*x^3 + C
7、=∫ sinxd(e^x)=e^x*sinx -∫ e^x*cosxdx
=e^x*sinx -∫ cosxd(e^x) = e^x*sinx - e^x*cosx -∫ e^x*sinxdx,
所以原式 = 1/2*(e^x*sinx-e^x*cosx) + C .
e^x (-Cos[x] + Sin[x]) /2
-(x^3/9) + 1/3 x^3 Ln[x]