超簡單微積分(急)!!!要求詳解

int x ln x dx
= int ln x d(x^2/2)
=(x^2/2) ln x - int (x^2/2) d( ln x)
=(x^2/2) ln x - int (x^2/2) (1/x) dx
=(x^2/2) ln x - int (x/2) dx
=(x^2/2) ln x - (x^2/4) +C

∫ x lnx dx

= (1/2) ∫ lnx d(x^2)

= (x^2/2)ln(x) - (1/2) ∫ (x^2)(1/x) dx

= (x^2/2)ln(x) - x^2/4 + C