I know. . .Calculus is a weeder class but my college son is already an excellent programmer. He got a 5 on the AP Java and AP Computer Science tests in high school and in fact already gets well paid coding jobs, but Calculus in college will be what stands in his way of getting his BS degree. He might have to take each semester of Calc twice in order to get past that hurdle.
Maybe consider hiring a tutor for that subject? He may need someone with better expertise to help him get through it.
We all had to memorize the quadradic equation back in the day. I still wonder if it has any practical use because I got damn near 50 years of work under my belt and have never used it since.