dv=x^(n)dx
du=(1/x) dx
v=[blue]x^(n+1)/(n+1)[/blue]; n ≠ -1
=x^(n+1)/(n+1)* lnx - ∫ x^(n+1)/(n+1) * (1/x) dx=
=x^(n+1)/(n+1)* lnx - (1/(n+1)) ∫ x^(n) dx=
=(x^(n+1)/(n+1))* lnx - (1/(n+1))*([blue]x^(n+1)/(n+1)[/blue]) + C=
=(x^(n+1)/(n+1))* lnx -(1/(n+1)^2) * x^(n+1) + C