Question

Let f(x) = (10 x^2 - 5)/(x^4 + 1).

Then f'(8)=?

Answer 1

use quotient rule and then sub x=8

Answer 2

(lodehi-hidelo) over lolo

Answer 3

when i plug in x i need to simplify?

Answer 4

hi is your numerator
lo is your denominator
dehi means take the derivative of the top
delo means take the derivative of the bottom
lolo is the bottom to the second power

Answer 5

lol

Answer 6

ok

Answer 7

so did you get it?

Answer 8

hold on let me do it first

Answer 9

http://www.wolframalpha.com/input/?i=find+the+derivative+of+%2810x%5E2-5%29%2F%28x%5E4%2B1%29
ok check yourself at wolframalpha

Answer 10

ok wow

Answer 11

did you get it?

Answer 12

then just plug 8 in

Answer 13

?

Answer 14

yes

Answer 15

just make sure you understand the process for an upcoming exam and you will be ok.

Answer 16

thanx

Answer 17

anytime. overall you are looking for the slope at that point.