Posted by Soroban on October 13, 2002 at 17:55:01:
In Reply to: need help with partial derivate... posted by tommy on October 13, 2002 at 16:06:04:
: u=x^(y/z)
: what are the partial derivates?
: du/dx=
: du/dy=
: du/dz=
With du/dx, only the x is a variable, the y/z is considered a constant,
We can use the Power Rule: du/dx = (y/z)x^(y/z - 1)
With du/dy, the y is a variable ~ we have a constant base.
We must use the Exponential Rule: If f(w) = a^w, then f'(w) = (a^w)*(w')(ln a)
So, du/dy = x^(y/z)*(1/z)*ln(x)
With du/dz, only the z is a variable.
Then du/dz = a^(y/z)*(-y/z^2)*ln(x)
Hope that made sense, Tommy.