If `u=log (x^(3) + y^(3) +z^(3) - 3xyz)`, then `(del u)/(del x) + (del u)/(del y) + (del u)/(del z)=`

If u=(x-y)^(2) , then (del u)/(del x) + (del u)/(del y) is

If u = log ((x ^(2) y + y ^(2) x)/(xy)) then x (del u)/( del x) + y (del u)/(del y)=

If u=x^y then find (del u)/(del x) and (del u)/(del y) .

If w(x,y,z) = x^(2)(y-z) + y^(2)(z-x) + z^(2)(x-y) , then (del w)/(del x) + (del w)/(del y) + (del w)/(del z) is

If U=(y)/(z)+(z)/(x), then find x(del u)/(del x)+y(del u)/(del y)+z(del u)/(del z) .

If u (x,y) =x ^(2) + 2xy-y ^(2) then (del u)/(del x) + (delu)/(del y) is:

If u=(x^(2)+y^(2)+z^(2))^(-1/2) show that x(del u)/(del x)+y(del u)/(del y)+z(del u)/(del z)=-u