Yes, I believe that you will need to study Mathematics Advanced content concurrently with Mathematics Extension 1 and Mathematics Extension 2 content. The difference lies in the fact that you will not be completing Mathematics Advanced assessment tasks/exams (this includes the HSC exam). Instead you will be required to complete assessment tasks/exams within the Mathematics Extension 1 and Mathematics Extension 2 courses (including the HSC exam for both subjects).
NESA states the following:
Mathematics Advanced consists of the courses Mathematics Advanced Year 11 and Mathematics Advanced Year 12. Students studying one or both Extension courses must study both Mathematics Advanced Year 11 and Mathematics Extension Year 11 courses before undertaking the study of Mathematics Extension 1 Year 12, or both Mathematics Extension 1 Year 12 and Mathematics Extension 2 Year 12.
Is it worth explicitly studying for 2u in that case at all? I heard of someone that ranked 1st in ext 1 and ext 2 at a school, then got mid-30s in adv. Do you have to care about your 2u internal rank if you're certain you will do well in 4u?
Sorry digging up an old thread, but is that all the topics that wont be tested in 3U/4U maths? Just wanna know so I can be aware of how much time I should spend on 2U maths from next term and what topics I can ignore to prioritise 4U.
You can spend as little as you need, as long as you are solid enough to apply the concepts in 3U and 4U. The analogy is they teach you integration in 2U but you'll need to know it for 3U and definitely 4U. I was lucky to accelerate 2U but I know many of friends did not and it was more stressful learning all three subjects at once.