I=2∫x2+1x2−1dx=2∫(x2+1x2+1−x2+12)dx=2∫(x2+1−x2+12)dx=2[2xx2+1+21ln(x+x2+1)−2ln(x+x2+1)+c=xx2+1+ln(x+x2+1)−4ln(x+x2+1)=xx2+1−3ln(x+x2+1)+c=U(x)⋅V(x)−3ln{U(x)+V(x)}+c∴U(x)=x and V(x)=x2+1\therefore \mathrm{U}(\mathrm{x}) \cdot \mathrm{V}(\mathrm{x})=\mathrm{x} \sqrt{\mathrm{x}^2+1}=\sqrt{\mathrm{x}^4+\mathrm{x}^2}=\sqrt{\mathrm{x}^2+\mathrm{x}^4}$