Hi,
Some additional information:
a) As for the systems of three linear equations, they came three times. In two cases, the equations had to expressed using matrices (multiple choice tests in 2006 - Problem 4, and in 2010 - Problem 5). This topic is no longer included in the curriculum. The only other occurrence was in the second part of Test 2 in 2009 (Problems 2a i and 2a ii). The solution could be found in a pedestrian way, and it is not impossible for this type of a problem to come up again.
b) As for the problems involving absolute values, I have not seen them after 2015. The current curriculum covers 2016-2020, and does not mention the absolute values explicitly. However, since students know what the absolute value is about, it is not illegal for the problems involving sketching or translating a function containing absolute values to pop up again in 2019.
c) In the past, i.e. before 2016, the tricky problems involving absolute values could be classified as follows:
(i) Determining which of the statements about the function is true or false: the multiple choice tests in 2007 (Problem
, 2008 (Problem 21), 2009 (Problem 14), 2010 (Problem 18), 2011 (Problem 16), 2012 (Problem 22), 2015 (Problem 18).
(ii) Solving equations as in the multiple choice test in 2006 (Problem 11), the second part of Test 2 in 2006 (Problem 1d), multiple choice test in 2009 (Problem 20).
(iii) Finding minimum and maximum, but without having to differentiate - the second part of Test 2 in 2006 (Problem 1a ii), and the multiple choice test in 2007 (Problems 6 and 14).
(iv) Really tricky problems involving differentiation - the second part of Test 2 in 2007 (Problem 3c) and 2009 (Problem 1e).
(v) Given that the formula for the differentiation of the absolute values of functions is no longer in the textbooks, you can give a miss to (iv), and on the balance of probabilities, the cases (i-iii) you can check out only if you have time.
Cheers, and please let me know if you find mistake in the text above, so it can be corrected immediately.