Question

Derivatives,

How do I find the derivative of a sumation ? (eg. https://www.dropbox.com/s/3un7mqdg9pjloxm/Screenshot%202016-02-02%2017.34.50.png?dl=0)

Answer 1

term by term.

derivative of (x1 - u)^2 will be -2(x1-u)
right?

same for all terms.

Answer 2

so,
\(\Large -2 \sum \limits_{i=1}^{n}(x_i-\mu )\)

try 2nd derivative also :)

Answer 3

http://www.sosmath.com/diffeq/series/series02/series02.html

Answer 4

I might be missing somethin - but why -2

Answer 5

why did it become negative @hartnn

Answer 6

- we though alike!

Answer 7

chain rule

Answer 8

\[\frac{d}{d\mu}(x_i-\mu)=-1\]

Answer 9

oh yes - the variable is the greek letter mu not the x.

Answer 10

chain rule,
\(\mu \) is the variable, \(x_i\)'s are constant.

same as finding derivative of (a-x)^2.