Melody

it is -1/12   

not -1 and a half  Brittany :))

yea I don't know either  LOL

there's that phi function again - it is sneaking in every where.

Thanks Heureka.  

How did you get that original 7^20 ?

You want e

On the site calc you can just enter e in the enter box.

On some calcs if you just want e you enter  e^1

I am not sure if that is any help   

tha is okay - why don't you join up.  ??

Maybe you already have?

I wondered what the relevance was of partial derivatives - now i have a better idea - thanks Alan. 

$$\\F=\frac{Gm_1m_2}{r^2}\\\\
F=\frac{9.8*7*7}{2^2}\\\\$$

and I guess the units have to be

$$\frac{m}{s^2}\times\frac{kg^2}{m^2}=kg^2/(ms^2)$$

You can finish it :)

$$x=5\qquad
S=2.5$$

befor i go any further are these the numbers you used?

you just look for what x and y can and cannot be.

Often it has to do with the fact that you cannot divide by zero. :)

yea they are all the same

gradient =gradient        LOL