They are different expressions of the same function. It doesn't matter which one you differentiate, you'll get the same result. Try and see
i have the fraction
f(x) = (x-8)/(x+2)(2x-1)
part (a) was to to express that into a partial fraction n i got
2/(x+2) - 3/(2x-1)
part (b) says
my question for part (b) is do i differentiate the original fraction or the partial fraction i found in part (a)???