Find the derivative of f(x) = negative 8 divided by x at x = 11.

Question

mrnood · Answer

$$f(x) = -8x ^{-1}$$

that is another way of writing the equation

use the standard rules for f'x

anonymous · Answer

THank you!

anonymous · Answer

so would it be 8/11

mrnood · Answer

no - you need to write the equation for f'(x) first, THEN put x=11 into that

remember - multiply by the power of x and then reduce the power by 1

(e.g. f(x) = x^2   =>> multiply by 2 and reuce power by one gives f'(x) = 2x)

SO

multiply by -1 and reduce -1 by 1.....

mrnood · Answer

-8x^-1

multiply by -1 ==???

anonymous · Answer

8x?

mrnood · Answer

no - I am giving you the fisrst step only for now 
-1*(-8x^-1) = ?

mrnood · Answer

do oyu know for instance how to do

derivative of f(x) = 3x^3

(This is just an example to find out what oyu can already do....)

multiply by th eexponent :==> 9x^3
reduce the exponent by 1  ==> 9x^2

so f'(x) = 9x^2


so follow the first step as I showed above:

-1*(-8x^-1) = ?

anonymous · Answer

8/x

mrnood · Answer

ok  now the second step  

REDUCE the exponent by 1 (8x^-1)