∫e3log x(x4+1)−1dx.
Let I=∫e3log x(x4+1)−1dx=∫elog x3(x4+1)dx=∫x3(x4+1)dx (∵ elog x=x)Put x4+1=t⇒4x3dx=dt⇒dx=dt4x3∴ I=∫x3tdt4x3=14∫1tdt=14log|t|+C=14log|x4+1|+C