∫ (lnx)^2/x^2 dx=-∫ (lnx)^2 d(1/x)=-(1/x) (lnx)^2 + 2∫ (lnx)/x^2 dx=-(1/x) (lnx)^2 - 2∫ (lnx) d(1/x)=-(1/x) (lnx)^2 - 2(1/x)(lnx) + 2∫ dx/x^2=-(1/x) (lnx)^2 - 2(1/x)(lnx) - 2/x + C=-(1/x) [ (lnx)^2 + 2lnx + 2 ] + C