(b) Let $I = \int_{}^{}\frac{x^{2}}{1 + x^{6}}\ dx$ Put $x^{3} = t\ \ \Rightarrow \ x^{2}dx = \frac{1}{3}\ dt$ $\therefore\ I = \frac{1}{3}\int_{}^{}\frac{1}{1 + t^{2}}\ dt = \frac{1}{3}\tan^{- 1}{(x^{3})} + c$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.