i generally don't [but i do 4unit and marks are generally allocated for the concepts and technique rather than whether the answer is rationalised or not], and it shouldn't matter, but some teachers get really picky [like the one where i wrote my answer as ln3-ln2 instead of ln(3/2) and got it wrong, even though there was no talk about simplifying the result]. it's ridiculous but to be safe, esp in two unit, i'd do it.