Thread: multivaribles 3??? caculus

let f(x,y,z)=2x^2y^2z + 4xy^3z^2 find fxyz(2,1,1)

do i have to find partial dervtive of fx and fy and fz and sub the value in?

Originally Posted by zangestu888

let f(x,y,z)=2x^2y^2z + 4xy^3z^2 find fxyz(2,1,1)

do i have to find partial dervtive of fx and fy and fz and sub the value in?

Is this what you're trying to find?

?

I don't think so. You would have to find then partial derivate it with respect to . Once you get this function, partial derivate with respect to .
Then evaluate this function in .
This method however doesn't work for all functions. For example the function .

In other words, you're finding



and then evaluating it at .

Yeah the book says find


does that mean i find fx then fxy then fxyz then find it at the point

Originally Posted by zangestu888

Yeah the book says find


does that mean i find fx then fxy then fxyz then find it at the point

It certainly does.