interesting that exam 1 8b only 3% got full marks on and the final question only 4%

Re, 8b, there are a few things on there that a very large proportion of the cohort would have overlooked or not applied under exam pressure.

1: Realising that e^(4x) > 0 for all x, hence the initial equation can be divided through by e^(4x) without losing solutions.

2: Getting a discriminant of 4 and being confused about how there could be only one solution with a positive discriminant.

3: Not realising that the second solution is discarded when division by zero occurs (rather than the square-rooting of a negative, which is a more common experience for students).

Most of these are subtleties that are more commonly addressed in Specialist. Of course one would expect students doing both subjects to have performed better on this question; but unfortunately often students compartmentalise their knowledge / skills, and don't apply relevant knowledge / skills across contexts.