In Exercises 7-10, find \( \nabla f \) at the given point.
7. \( f(x, y, z)=x^{2}+y^{2}-2 z^{2}+z \ln x, \quad(1,1,1) \)
8. \( f(x, y, z)=2 z^{3}-3\left(x^{2}+y^{2}\right) z+\tan ^{-1} x z, \quad(1,1,1) \)
9. \( f(x, y, z)=\left(x^{2}+y^{2}+z^{2}\right)^{-1 / 2}+\ln (x y z), \quad(-1,2,-2) \)
10. \( f(x, y, z)=e^{x+y} \cos z+(y+1) \sin ^{-1} x, \quad(0,0, \pi / 6) \)