Subject: Math problem!

I get a different sign

f'(x) = (1+x^2)^(-3) * (-6x^2+2)

first, transform it into:
f(x)=2x/[(1+x^2)^2]
it seems the sign is wrong in the answer

thanks. and actually it was my mistake, not the books mistake:Ü

f(x)=... * (-2x) not (2x)

but yea, got the same result now.

I have a 'Math problem', it's called the whole of the Additional Maths course! :(

looks more like a brain disfunction than a math problem imho:P

I've passed my GCSE with a B, and I'm still resitting.

6 and a half hours in the exam hall this Summer purely for Maths.

math is overrated im tellinya. people just say its difficult, because they´ve herd someone say its difficult so they believe it and give up.

Lloyd is not re-sitting the additional maths just in case anybody gets confused :)

I am also re-sitting Maths after getting an A. In theory, should be "easier" considering we have learnt the Additional course.

In school math is not really complicated, if you sit down and learn it is maybe not a piece of cake if you are not "talented" but it is possible to achieve good grades.

If you get the basics only the sky is the limit in math.

And the millenium problems.

I'm resitting the 'Higher' Maths paper, after getting a B, whilst sitting the 'Additional' for the first time, based on the actual paper, I'm hoping for a C. :P

could anybody help me with this one:

x^2 + y^2 + z^2 < = 1

T(x,y,z) = y^2 + xz

find T max and min
(edited)

x^2 + y^2 + z^2 >= 1

You're sure this is the right condition or do you mean 'less than or equal to one' ?

yeap, should be smaller or equal, my bad
(edited)

.
(edited)

To find local extreme values you have to use partial differentiation. That gives:

d/dx T(x,y,z) = z
d/dy T(x,y,z) = 2y
d/dz T(x,y,z) = x

A necessary condition for a point (a,b,c) to be an extreme value of T is, that all partial derivatives vanish. That is only fulfilled by one point. You have to check now if that point is really an extreme value and if it is not one, where would you find the extreme value then, if not by partial differentiation?