Maths help

FrostedNipple · 5 May 2008 at 20:29

Got stuck differentiating this

(3x^2) + (-2x) + (xy)* + (y^2) (-11) = 0

i get this

d/dx = (6x) + (-2) + ((y) + (x dy/dx))* + (2y dy/dx)

*product ruled it

i bracketed it so you can see which bits came from where

Its part of a question to find the normal to the curve at p p=(-1,3) for those interested. I'm able to do the rest after i figure out what to do with the differentiation

Cheers

[TR]SweetSpotOz · 5 May 2008 at 20:33

FrostedNipple · 5 May 2008 at 20:36

thats what i thought, but i've got an x and a y :/ is that ok?

i would get

6x -2 +y = -2y dy/dx -x dy/dx

[TR]SweetSpotOz · 5 May 2008 at 20:37

Flanders · 5 May 2008 at 20:38

Factorise.

Inquisitor · 5 May 2008 at 20:40

You got the differentiation right – you just need to equate that expression to zero and factorise:

FrostedNipple · 5 May 2008 at 20:42

ahh ok, so you can mix the x and the y, thanks marky

don't worry Flanders, i won't forget to factorize :rolleyes:

edit - thanks for backup proof inquisitor

[TR]SweetSpotOz · 5 May 2008 at 20:42

FrostedNipple · 5 May 2008 at 20:48

open office - math is pretty good for equation writing word works well too, insert equation tool

Mansize_tissue · 5 May 2008 at 20:49

markyp23 said:
How did you make that - Word? Would help when I talk to friends on msn when stuck on maths!

Latex maybe?

Inquisitor · 5 May 2008 at 20:51

markyp23 said:
For the sake of saving my own face with the non-maths people my answer is the same as your's lol.

EDIT: How did you make that - Word? Would help when I talk to friends on msn when stuck on maths!

Word 2007 + cropper to take a localised screenshot