Question

I need help with these two questions. I'm not getting the same answer in the back of the book.

f(x) = (1+x^4)/(x^2)
for which I got (6x^5-2x)/(x^4)
and the answer at the back is (2x^4-3)/(x^3)

And this question I don't get at all.

f(x) = (5-(1/x))/(x-3)

Answer 1

What are we doing here? Differentiation?

Answer 2

first derivative line :

f'(x) = [x^2(4x^3) - 2x(1+x^4)]/x^4
= [4x^5 - 2x - 2x^5]/x^4
= (2x^5 - 2x)/x^5 , now divide each term by x
= (2x^4 - 2)/x^3

looks like both you and the back of the book are wrong!