Why are generic pharmaceuticals significantly cheaper than the name brand ones?

Refer to text, be sure to cite any references - Chapter 9 https://openstax.org/books/principles-economics/pages/9-introduction-to-a-monopoly

Many firms in the United States file for bankruptcy every year, yet they still continue operating. Why would they file bankruptcy instead of completely shutting down?

Refer to text, be sure to cite any references - Chapter 8

https://openstax.org/books/principles-economics/pages/8-introduction-to-perfect-competition