my teacher was in a rush at the end of the class and he literally only spent 5 minutes on summations, so i'm kinda confused here.
oh and also if you can, i think i got it right, but i always make some dumb mistakes on these long ones
find the derivative y = (2x^7 - x^2)(x - 1/x + 1)
just the answer would be enough for this last one, if it doesn't match then i'll check my math again.
Love ya guys!