$$ \int \frac{1}{1+x^4}dx $$

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/3f92c501-cba9-4f78-b41a-8827d58fa0d4/image.jpg


$$ \int \frac{e^{3x}+e^x}{e^{4x}-10e^{2x}+1}dx $$

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/a9c392ba-0a51-4049-af99-6c5736c627b8/image.jpg


$$ \int \sin 3x \cos x dx $$

高等数学-三角函数