Would you lose marks in the HSC for not completely simplifying, as in being about one step away from the simplified answer ?
The HSC marker guidelines specify how the markers are to mark, they typically require simplification, but it depends on the question.
If you have a question, lets say find the derivative of
A version of the correct answer is:
But, the simplified correct answer is:
It is likely that you will not get the final answer mark unless you present the simplified answer.
Regardless, you should always be trying to simplify wherever possible.