∫(ln²x)dx其中u v怎么设的?,

令a=lnx
x=e^a
dx=e^ada
原式=∫a²*e^ada
=∫a²de^a
=a²*e^a-∫e^ada²
=a²*e^a-2∫ade^a
=a²*e^a-2a*e^a+2∫e^ada
=a²*e^a-2a*e^a+2e^a+C
=x*ln²x-2xlnx+2x+C