(b) $\int_{}^{}e^{3\log x}\ \left( x^{4} + 1 \right)^{- 1}dx$ $= \int_{}^{}\frac{x^{3}}{1 + x^{4}}\ dx = \frac{1}{4}\log{\left( x^{4} + 1 \right) + c}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.