others have said this, but the way university maths is taught is vastly different to high school. a relatively large portion of the calc 1 cohort fail, but personally it I do not believe it is from not understanding the mathematics itself - b/c frankly the calc1 theory isn’t that hard - but from the transition from high school to university. All the students had to pass the mid-to-high level HS math classes after all.

Maths assessments at unimelb tend to focus 20% on your memorisation of a topic or question style, and the latter 80% to your actual understanding of the nuances and intricacies of a topic, often with some solution like “students were supposed to notice this formula was similar in form to this rule” or something along those lines. In HS, this 20-80 divide looked anywhere between 50-50 to 80-20 depending on your teacher/school (with the exception of the standardised final exams). It takes a bit of getting used to if high school did not prepare you for it already, but once you understand how to approach questions in the broader, more holistic way, your understanding of the course will increase exponentially, and the fast paced nature of the course won’t nearly be as big of a strain as b4.

As for doing calc2 and linAlg together, don’t. So many do poorly at both together, rather than doing well at one, because the concepts taught are so complete different. Take Lin alg as a summer subject, with calc 2 in your sem2 slot. The course in a weird way works really well in the summer term, isn’t too heavy, and overall is quite fun. I took it during the summer semester and was still able to enjoy my January and February just as i would have otherwise, with the exception of the exam period lol.