Thread: Question on derivative

hi everyone,

Find$\displaystyle \frac{dz}{dx} and \frac{dz}{dy}$
xyz-cos(x+y+z)=0


i am having problems with the cos(x + y + z).

Thank you in advance for all your help & support.

Originally Posted by anderson

hi everyone,

Find$\displaystyle \frac{dz}{dx} and \frac{dz}{dy}$
xyz-cos(x+y+z)=0


i am having problems with the cos(x + y + z).

Thank you in advance for all your help & support.

What is your problems exactly in $\displaystyle cos(x+y+z)$ ?

hi General,

is this correct?

F(x,y,z) = xyz - cos(x + y + z)

$\displaystyle F_x$=yz+sin(x+y+z),

i dont know how to get sin(x+y+z), u = (x + y + z),i dont know how to continue from there to get sin(x+y+z)

thank you for all your help & support.

Originally Posted by anderson

hi General,

is this correct?

F(x,y,z) = xyz - cos(x + y + z)

$\displaystyle F_x$=yz+sin(x+y+z),

i dont know how to get sin(x+y+z), u = (x + y + z),i dont know how to continue from there to get sin(x+y+z)

thank you for all your help & support.

Sorry I will reply to this. Since General is offline.

Your $\displaystyle F_x$ is correct.

In general, If $\displaystyle h$ is differentiable, then:
$\displaystyle \frac{\partial}{\partial x}( \,\ cos( \, h(x,y,z) \, ) \,\ ) = -sin( \, h(x,y,z) \, ) \, \frac{\partial}{\partial x}( \, h(x,y,z) \, )$.

Did you get it ?