higher-order derivative

i'm so tired now! for the past week i've been travelling back and forth between home, school and hospital, sleeping late, and waking up early, feeling sleepy for the promotional examinations. well, mum's discharged now and examinations are over, so that's better. but i'll still have to do lots of housework and wash clothes and iron clothes! there's oral presentation to do for project work, and i've got programme notes to write for my violin examination. i'm going to die of stress again, just spent the past two hours writing a draft of the programme notes.