You have no idea how retarded I feel... I found a common denominator once I'd differentiated (mindlessly), and the resultant expression was impossible to solve. The entire time I was staring at it (and it was a long time believe me, I found the previous 9 questions VERY easy, even compared to previous HSC's), the thought of cross multiplying didn't cross my mind once.I should not have made a common denominator in part i, haha crap it would've been so much easier. I have been a fool.
I feel so stupid.