Yeah need to know this!
Especially for example 2013 exam 2 for the last page
Sorry to destroy hopes but this wouldn't work on the question you are talking about on exam 2 2013. The problem is, the answer to the "lockout question" where you needed to find m in terms of k is ALGEBRAIC, and is not a simple number. Furthermore, its actually a function because its defined for 5 <= k =< 8. What that means is that any working you do for the question where you let a = "answer" is a simplification of the problem and a generalization.
It would be the equivalent of writing the answer to Q1 a) i) on every exam 1 (which is generally always a 2 mark product rule diff questions) as dy/dx = dy/du * du/dx and nothing more. You would never get marks for doing that even though its absolutely correct because its a generalized solution and VCAA wants an exact one.
That's why if you look at the mark percentages for the question, less than 10% got the marks for the rest of Q4, even though so many claim to have tried to get consequential marks.
Don't waste your time doing working on consequential questions that have an algebraic answer if you didn't get the answer to the lockout question, you will never receive any marks on them even if your working is 100% correct. You're far better off checking the rest of your paper if you've exhausted everything to try to figure out the lockout question to no avail.