Question

已知f(x)=e^-2x.求不定积分f(lnx)/x.dx

Answer 1

f(lnx)

=e^(-2lnx)

=e^(lnx^-2))

=x^-2

所以原式=∫x^(-3)dx

=x^(-3+1)/(-3+1)+C

=-1/(2x²)+C