The unit normal vector to the surface \(2xy-y^3+x z=3 \ \)at point (1,-1,1) is
1
\(\frac{-\hat i-\hat j+\hat k}{\sqrt 3} \ \)
2
\(\frac{\hat i-2\hat j+\hat k}{\sqrt 6} \ \)
3
\(\frac{-\hat i+\hat j+\hat k}{\sqrt 3} \ \)
4
\(\frac{-\hat i-2\hat j+\hat k}{\sqrt 6} \ \)